Solve  the  problem 
of  self-instruction 
in  the  International 
Morse  Code 


BY  USING  THE  NEW 


MARCONI -VICTOR 


Wireless 
Code 

Instruction 
Records 

The  Marconi  Institute 
In  collaboration  with 
The  Victor  Talking 
Machine  Company 

has  prepared  a  complete  set  of  Code 
Instruction  Records  for  private 
study. 

A  series  of  progressive  lessons  pro- 
vides elementary  and  advanced  in- 
struction for  men  in  all  divisions  of 
Government  and  commercial  service. 

Records  made  by  a  code  expert  of 
years  of  practical  experience. 

Officially  approved  by  The  Mar- 
coni Wireless  Telegraph  Company  of 
America. 


Brief  Summary  of  Records 

Lesson 

No.  Title 

i— International  Morse  Code  and  Conven- 
tional signals. 

2—International  Morse  Code,  etc.,  continued. 

3 — Easy  sentences  and  periods. 

4— Easy  sentences  and  periods. 

5 — Marconi  Press,  South  Wellfleet  station. 

6 — Messages  with  static  interference. 

7 — Press  with  static. 

8 — Messages  with  erasures,  etc. 

9 — Press  with  interference  from  second  sta- 
tion. 

10 — Groups  of  figures. 

ii — Ten-letter  dictionary  words. 

12 — Ten-letter  code  words. 

A  set  of  six  double-faced  Victor  Records, 
complete  in  a  container  with  instruction  man- 
ual, specially  priced  at  $5.00. 

WIRELESS  PRESS,  Inc. 

25  Elm  Street,  NEW  YORK  CITY 


MANUAL  OF  THE 

MARCONI  INSTITUTE 


FOR  TRAINING  IN 
RADIO  COMMUNICATION 
AND  ALLIED  VOCATIONS 


HEADQUARTERS 
Edison  Building,  25  Elm  Street 

Cor.  Duane  Street 

New  York  City 


BRANCHES 

Cleveland*  Ohio:   Lenox  Building,  Rooms  361-70 
Euclid  Avenue  and  East  9th  Street 

San  Francisco,  Gal.:  New  Call  Building 
New  Montgomery  Street 


MARCONI  INSTITUTE 


BOARD  OF  MANAGERS 

GUGLIELMO  MARCONI 

Honorary  Chairman 

HON.  JOHN  W.  GRIGGS 
Chairman 

EDWARD  J.  NALLY 
President 

DAVID  SARNOFF 

Managing  Director 

ELMER  E.  BUCHER 

Director  of  Instruction 

ALONZO  FOGAL,  JR. 

Director  of  Extension  Service 

J.  ANDREW  WHITE 

•  Director  of  Vocational  Training 

ROY  A.  WE'AGANT"   5  :**;•.." 
•\\  I  tMrtf&p'p  *6/  •R&seareli 

HERBERT  G.  OGDEN 

Director  of  Patent  Research 

JOHN  BOTTOMLEY 
Treasurer 

CHARLES  J.  Ross 

Comptroller 

W.   A.   WlNTERBOTTOM 

Superintendent  of  Branches 


CONTENTS 

PAGE 

A  WAR-TIME  MESSAGE 5 

THE  INSTITUTE'S  OFFER  TO  TECHNICAL  SCHOOLS 9 

OPPORTUNITIES  IN  THE  RADIO  FIELD 11 

TRAINING  METHODS 16 

QUALIFICATIONS  OF  STUDENTS  (FEDERAL  VOCATIONAL  BOARD)  ....  25 

COURSES  OF  INSTRUCTION  AT  THE  MARCONI  INSTITUTE 29 

THE  INSTITUTE  EXTENSION  COURSE 41 

WIRELESS  AGE    42 

TEXTBOOKS  AND  SPECIAL  WIRELESS  LITERATURE 44 

THE  MARCONI  WIRELESS  RECORDS    50 

CREATION,  GROWTH  AND  DEVELOPMENT  OF  THE  MARCONI  WORLD- 
WIDE SYSTEM 51 

SCIENTIFIC  PROGRESS  OF  THE  ART 67 

INSTITUTE  OF  RADIO  ENGINEERS 76 

NATIONAL  WIRELESS  ASSOCIATION  .    77 


379923 


MARCONI    INSTITUTE 

A    WAR-TIME    MESSAGE 

T  OYAL  citizens  of  the  United  States,  in  the  present  national  crisis, 
•*— '  are  called  upon  as  never  before  to  cast  aside  all  personal  ambitions 
in  the  interest  of  world  democracy.  It  matters  not  how  promising  a 
policy  may  have  been  laid  out  for  future  welfare.  All  selfish  plans  of 
the  individual  must  temporarily  be  laid  aside.  For  a  time  the  services 
of  Americans  must  be  at  the  disposal  of  the  Government.  What  we  do 
we  must  do  well. 

Unlike  previous  wars,  this  one  is  a  conflict  of  scientific  forces  with   ! 
a  definite  ethical  and  broad  humanitarian  principle  at  stake,  and  the 
individual   must   not   make   the  blunder   of   approaching   the  problem   ; 
unprepared.     Skilled  workers  are  required  in  all  branches  of  the  Army 
and  Navy.     Men  who  possess  no  other  qualifications  than  mere  ability 
to  perform  manual  labor  are  limited  in  their  usefulness. 

Foremost  of  all  qualifications  at  this  period  is  technical  education. 
Whether  in  the  interest  of  peace  or  of  war,  the  man  sought  for  is  the 
one  who  understands  the  why  and  wherefore  of  things  with  which  he 
deals  in  his  everyday  environment. 

So  important  is  the  matter  of  supplying  our  Army  and  Navy  with 
skilled  workers,  and  keeping  our  workshops  filled  with  technically 
trained  men,  that  the  Scientific  American  recently  remarked  editorially : 

If  we  are  in  for  a  long  war  then  it  is  equally  important 
from  a  military  point  of  view  to  add  to  the  brain  power  of 
the  nation  by  increasing  the  attendance  at  universities,  col- 
leges, normal  schools,  and  technical  schools — now  constitut- 
ing a  little  more  than  one-half  of  one  per  cent,  of  the  total 
population  of  productive  age.  .  .  .The  hours  of  the  classes 
and  the  length  of  the  course  should  be  arranged  so  as  to  give 
students  better  opportunities  for  "working  their  way" 
through  college ....  We  must  have  more  and  more  technically 
trained  men  whether  for  War  or  Peace — .  .  .  .more  experts 
in  every  line. 

The  opportunities  for  well-trained  and  properly  educated  workers 
at  the  close  of  the  war  will  be  even  greater.  DR.  KLAXTON,  U.  S.  Com- 
missioner of  Education,  states : 

When  the  War  is  over,  whether  within  a  few  months  or 
after  many  years,  there  will  be  such  demands  upon  this  coun- 

5 


MARCONI    INSTITUTE  7 

try  for  men  and  women  of  scientific  knowledge,  technical  skill, 
and  general  culture  as  have  never  come  before  to  any  country. 
The  world  must  be  rebuilt.  This  country  must  play  a  far 
more  important  part  than  it  has  in  the  past  in  agriculture, 
manufacturing,  and  commerce.  .  .  .Russia  and  China  are 
awakening  to  new  life  and  are  on  the  eve  of  a  great  industrial 
development.  They  will  ask  of  us  steel,  engines  and  cars  for 
railroads,  agricultural  implements,  and  machinery  for  indus- 
trial plants.  They  will  also  ask  for  men  to  install  these  and 

to  direct  much  of  their  development  in  every  line. 

1 

The  industrial  progress  and  power  of  any  nation  depends  abso- 
lutely upon  the  maintenance  of  rapid  means  of  intercommunication. 
At  the  close  of  this  war,  no  scientific  development  will  expand  com- 
mercially at  a  more  rapid  rate  than  the  art  of  wireless  communication. 
The  war  has  given  great  impetus  to  the  art,  both  from  a  commercial 
and  a  scientific  standpoint.  A  far  greater  expansion  will  take  place 
when  hostilities  cease. 

Already  the  genius  of  our  nation  has  bent  its  energies  toward  the 
perfection  of  needful  improvements  in  radio,  and  as  the  result  of  this 
forced  concentration  discoveries  of  immeasurable  importance  have  been 
made.  Twenty-four  hour  wireless  communication  from  continent  to 
continent  is  now  an  assured  fact.  It  will  not  be  long  before  every  out- 
lying island,  every  vessel,  every  isolated  settlement,  will  have  a  radio 
station  as  a  link  in  a  universal  system  of  wireless  intercommunication." 
This  great  expansion  will  require  an  army  of  skilled  research  engineers, 
inspectors,  operators,  and  installers. 

In  view  of  this  situation,  a  direct  appeal  is  made  to  Americans: 
Will  you  serve  your  country  in  advancing  a  most  remunerative  and 
most  fascinating  profession,  or  will  you  stand  by  while  others  occupy 
the  field?  All  countries  are  culling  for  radio  men.  Your  Government 
needs  them  now! 

The  professional  radiotelegraphist,  to  properly  perform  the 
simplest  duties  in  the  operation  of  wireless  telegraph  apparatus,  must 
be  a  skilled  man. 

He  must  have  a  thorough  education  in  the  fundamental  principles 
of  electricity  and  magnetism ;  must  understand  the  operation  of  dyna- 
mos and  motors ;  must  be  familiar  with  the  general  theory  of  alternat- 
ing currents  and  have  an  intimate  knowledge  of  the  radio  frequency 
currents  which  are  employed  in  wireless  transmitting  and  receiving. 

The  United   States   Navy   requires   immediately   several   thousand 


MARCONI    INSTITUTE  9 

skilled  radiotelegraphists  and  the  Army  Signal  Corps  will  require  the 
services  of  more  than  30,000  trained  men. 

The  training  is  a  big  task.  It  can  be  brought  to  a  successful  con- 
clusion only  by  educational  institutions  throughout  the  country  open- 
ing up  their  facilities  for  instruction  and  co-operating  fully  with  the 
Government. 


THE  INSTITUTE'S  OFFER  TO  TECHNICAL  SCHOOLS 


Institute  has  engaged  in  the  work  of  training  radiotelegraphists 
for  the  past  nine  years,  and  during  this  period  has  graduated  more 
than  3,000  men,  ninety-nine  per  cent,  of  whom  have  been  placed  in  com- 
mercial positions.  Many  are  now  in  the  Government  service. 

The  directors  of  the  Institute  believe  that  for  the  present  it  can 
serve  our  country  in  no  more  effective  and  patriotic  manner  than  by 
freely  offering  counsel  and  aid  to  radio  schools  now  in  operation,  and 
to  technical  schools  in  process  of  forming  radio  classes  to  assist  our 
Government. 

The  Institute  stands  ready  to  help  all  such  schools  in  every  possible 
way,  particularly  in  outlining  a  definite  classroom  course  for  technical 
and  code  instruction.  This  is  not  an  entirely  new  function  of  the 
Institute  ;  it  has  acted  in  a  similar  advisory  capacity  to  training  schools 
throughout  the  world,  particularly  since  the  United  States  entered 
the  war. 

The  Board  of  Managers  invite  all  universities,  colleges,  or  public 
schools  throughout  the  country  contemplating  the  training  of  radio- 
telegraphists  on  behalf  of  the  United  States  Government,  to  freely 
present  to  them  any  problems  which  may  arise  in  the  forming  of  radio 
schools. 

The  outline  prepared  by  the  Institute  gives  a  complete  course  of 
training  and  the  approximate  figures  covering  the  expense  of  apparatus 
required  and  the  cost  of  installation. 

The  need  for  well-trained  men  is  urgent  at  this  moment,  and  after 
the  war  the  demands  for  professional  radiotelegraphists  will  be  such 
that  it  will  be  difficult  to  find  men  to  fill  the  new  positions  created. 
Hence  the  outlined  training  course  prepared  equips  the  student  for 
Government  service  now  and  places  him  in  line  for  holding  a  responsible 
position  when  the  war  is  ended. 


MARCONI   INSTITUTE  11 

Attention  is  directed  to  the  technical  literature,  listed  in  this 
manual,  compiled  with  the  assistance  of  prominent  American  educators. 
The  directors  have  instituted  a  special  extension  training  service  which 
will  keep  instructors  and  students  in  touch  with  the  best  current  litera- 
ture of  the  radio  art. 

This  service  is  rendered  without  charge. 


OPPORTUNITIES  IN  THE  RADIO  FIELD 

great  commercial  development  in  wireless  telegraphy  which  is 

bound  to  follow  the  world  war  has  been  referred  to.  The  conclusions 
are  definite  and  authoritative,  for  they  are  based  on  careful  study  of  the 
trend  of  industrial  development  and  exceptional  opportunities  to  observe 
the  operations  of  the  commercial  companies. 

At  the  opening  of  the  war  in  1914,  there  were  in  the  world  approx- 
imately 700  land  stations  and  4,500  ship  stations.  These  stations  were 
engaged  in  public  correspondence,  Navy  and  Army  communication,  the 
service  of  lightships  and  lighthouses,  and  represent  ownership  by  com- 
mercial companies,  Governments,  and  individuals. 

Vast  extensions  have  taken  place  since  the  beginning  of  the  world 
war.  Definite  figures  are  not  permitted,  but  it  may  be  said  that  wire- 
less is  employed  almost  exclusively  for  trench  warfare  communication, 
and  for  directing  artillery  fire  from  airplanes.  It  has  proved  invaluable 
to  scout  patrol  boats,  torpedo  boat  destroyers  and  the  hundreds  of 
other  naval  vessels.  Millions  of  dollars  in  cargo  and  thousands  of 
human  lives  have  been  saved  through  the  elaborate  system  of  radio 
communication  which  all  nations  have  established. 

Already  wireless  telegraphy  is  installed  on  several  thousand  ves- 
sels equipped  by  the  affiliated  Marconi  Companies  and  others,  and  by  the 
Army  and  Navy  forces  of  every  country  in  the  civilized  world.  Conti- 
nents have  been  connected  together  by  a  world-wide  communication 
system,  and  although  these  stations  are  temporarily  under  Government 
control  they  will  be  opened  for  public  service  at  the  close  of  the  war. 

To  the  highly  skilled  employees  required  for  this  service  must  be 
added  five  thousand  skilled  operators  needed  in  the  next  twelve  months 
for  the  new  American  merchant  marine  to  fulfill  the  program  of  the 
Federal  Shipping  Board. 

It  will  not  be  long  before  radio  men  may  be  required  in  the  fol- 


MARCONI    INSTITUTE  13 

lowing  special  fields  for  service  which  wireless  telegraphy  will  be  called 
upon  to  render : 

( 1 )   As  AN  AUXILIARY  TO  RAILROADS  : 

Wireless  telegraphy  has  been  successfully  employed  by  one 
of  the  foremost  railroad  systems  in  the  United  States  and  has 
rendered  service  in  the  despatch  of  trains  when  the  wire  systems 
were  paralyzed  by  storms. 

Communication  has  been  established  and  maintained  with 
moving  trains. 

Sections  in  the  great  West  where  it  is  difficult  to  maintain 
wrires  will  employ  radio. 

(2)   As  AN  AUXILIARY  TO  EXISTING  WIRE  SYSTEMS: 

The  interruptions  to  which  wire  lines  are  subject  through 
heavy  sleet  and  wind  storms  are  well  known.  Thousands  of 
dollars  have  been  lost  by  business  houses  accustomed  to  rely 
upon  telegraph  communication  for  the  transaction  of  business. 
Wireless  systems  have  been  perfected  to  the  point  where  they 
can  be  relied  upon  for  accurate  service  throughout  the  hours 
of  the  day.  Radio  gives  a  first  class  service  independent  of 
weather  conditions. 

(3)  THE  CITY  POLICE  SERVICE: 

For  the  police  headquarters  of  every  city  of  importance, 
connection  by  radio  with  other  cities  within  a  few  hundred  miles 
is  essential.  Outlying  police  stations  within  the  larger  cities 
must  be  joined  by  radio  so  as  to  form  a  complete  system,. inde- 
pendent of  wire  communication.  Police  ambulances  and  emer- 
gency wagons  will  be  equipped  with  apparatus  for  communica- 
tion with  headquarters  during  riots,  fires,  and  other  disturb- 
ances. 

No  system  can  equal  radio  for  the  despatch  of  orders  for 
apprehending  criminals.  Such  messages  could  be  broadcasted  to 
several  hundred  cities  simultaneously  with  one  transmission. 

(4)  IN  FORESTRY  DEPARTMENTS  : 

Nothing  can  equal  radio  as  a  system  of  communication  for 
reporting  forest  fires.  By  means  of  large  stations  erected  at 
strategic  points  in  the  forest  reserves  and  by  the  use  of  smaller 
portable  stations,  fires  can  be  quickly  reported  and  the  for- 
esters mobilized  for  action. 


MARCONI    INSTITUTE  15 

(5)   IN  INLAND  WATER  SYSTEMS: 

The  assured  revival  of  water  freight  and  passenger  routes 
on  the  rivers  and  inland  waters  of  the  United  States,  will  call  for 
numerous  stations  in  river  and  lake  cities  and  on  vessels. 


(6)   TIME  SERVICE: 

Accurate  time  service  can  be  better  furnished  by  wireless 
than  by  land  lines.  By  means  of  a  simple  receiving  station 
tuned  to  a  central  transmitter,  time  service  can  be  supplied  with 
greater  accuracy  than  by  wire,  owing  to  the  elimination  of  the 
lag  in  telegraph  relays. 


(7)   FISHERY  FLEETS  : 

These  fleets  will  be  more  extensively  equipped  with  radio 
apparatus  than  ever  before.  The  advantages  accruing  to  such 
fleets  by  the  use  of  radio  lie  in  the  rapid  despatch  of  informa- 
tion concerning  the  most  favorable  fishing  grounds,  market 
conditions  and  the  weather. 


(8)    Ix    SOUTH    AMERICA,    AFRICA,    CHINA,    RUSSIA    AND    OTHER 
COUNTRIES  IN  WHICH  WIRE  SYSTEMS  ARE  NOT  EXTENSIVE  : 

Otherwise  impassable  mountain  ranges,  jungles  and  widely 
separated  cities  in  the  above-mentioned  countries  will  require 
complete  systems  of  wifeless  communication,  such  as  has  been 
perfected  in  the  Philippines.  The  number  of  stations  and 
trained  employees  required  to  carry  on  this  work  and  training 
will  be  such  as  to  tax  all  existing  facilities. 


(9)  IN  THE  GOVERNMENT  WEATHER  BUREAU: 

This  department  of  the  Government  in  all  countries  requires 
a  very  extensive  wireless  system  for  rapid  transmission  of 
weather  reports  and  for  collecting  data. 


(10)    IN  MINING  REGIONS: 

As  demonstrated  in  Alaska  and  in. the  Peruvian  Andes,  iso- 
lated communities  will  require  a  complete  chain  of  wireless  sta- 
tions to  keep  in  touch  with  one  another.  Particularly  will  such 
means  of  communication  be  required  in  event  of  local  disturb- 
ances. 


16  MARCONI    INSTITUTE 

(11)      PRESS  ASSOCIATIONS: 

Wireless  is  especially  adapted  to  this  sort  of  work  because 
a  single  transmitting  station  can  dispatch  newspaper  reports 
simultaneously  to  several  hundred  receiving  stations ;  in  fact, 
to  as  many  stations  as  may  be  necessary. 

There  is  not  the  slightest  doubt  that  the  day  is  at  hand  when  all 
continents  will  be  completely  joined  together  commercially  by  high- 
power  wireless  stations  and  a  business  will  develop  that  will  exceed  the 
present  total  business  of  the  cables  of  the  world. 

Wireless  can  perform  this  service  with  the  accuracy  of  the  cable 
and  at  a  fraction  of  installation  and  maintenance  expense. 

An  immense  demand  for  radio  men  is  assured  for  the  immediate 
future.  The  supply  of  skilled  workers  in  this  field  is  always  below  the 
requirements  of  the  day;  the  student's  opportunities  may  be  judged 
by  the  present  conditions  and  the  future  possibilities  as  outlined. 


TRAINING  METHODS 

-•'jhiv/    ban   no 

I^L'TD'  one7  Isr  qualified  to  manipulate  wireless  telegraph  apparatus 
!•*  7  merely  bacause  he  possesses  knowledge  of  the  Continental  telegraph 
,£9jijfijr,  {Ifu^ther,,  the  professional  radio  telegraphist  must  have,  not 
merely  a  knowledge  of  the  operation  of  equipment,  but  also  sufficient 
fundamental  knowledge  to  enable  him  to  do  installation  work,  to  effect 
repairs,  and  to  devise  special  means  for  solving  any  immediate  problems 
which  may  arise.  Such  work  cannot  be  performed  without  at  least  a 
;^Mii!rim.a'ii^'(te'6h1n'ical  preparation  based  on  knowledge  of  elementary 
'electricity  'ana  magneti sm . 

To  standardize  technical  instruction  in  radio-telegraphy,  the  Insti- 
tute presents  the  following  outline,  with  subjects  considered  in  the 
^flej7,)pff^he)i^iim-p0j'tance.  It  is  based  upon  the  most  successful  prac- 
-titee  ^Jloniredironfrpriparing  thousands  of  students  for  entry  into  com- 
(mWciaF  service? '''Gft*  covers  fully  the  basic  principles  underlying  the 
operation' 01  tfte  transmitting  and  receiving  apparatus  in  a  complete 
radio  system. 


MARCONI    INSTITUTE  17 

The  subjects  to  be  treated  in  theory  and  in  practice  are: 

(1)  Primary  and  secondary  cells. 

(2)  The  theory  of  dynamos  and  motors. 

(3)  The  special  phenomena  of  alternating  current  cir- 
cuits. 

(4)  The  design,  construction,  and  operation  of  motor- 
generators  including  the  dynamotor,  rotary  converter,  hand 
and  automatic  motor  starters. 

(5)  The  high  voltage  transformer. 

(6)  The  high  voltage  condenser. 

(7)  High   frequency   oscillation    circuits   in   radio    tele- 
graphy. 

(8)  Radiating  circuits  in  radio  telegraphy. 

(9)  Coupled  transmitters. 

(10)  Wireless  telegraph  aerials  or  antenna. 

(11)  The  principles  of  resonance  and  tuning. 

(12)  Fundamental  receiving  circuits. 

(13)  Practical  wireless  measurements. 

(14)  Undamped  oscillation  transmitters. 

(15)  Undamped  oscillation  receivers. 

To  keep  pace  with  the  progress  of  the  past  few  years,  instructors 
are  urged  to  teach  students  to  recognize  the  present  tendency  towards 
the  universal  adoption  of  compact  panel  transmitters,  and  the  special 
problems  involved,  owing  to  the  close  assembly  of  the  apparatus. 

Specially  designed  radio  apparatus  for  airplanes  and  submarines 
should  be  explained  in  detail. 

Modern  regenerative  beat  receivers,  in  other  words,  the  oscillating 
vacuum  valve  circuits,  on  account  of  their  importance  in  long  distance 
work,  should  be  treated  in  general  and  in  detail.  Such  instruction 
should  bear  only  on  modern  apparatus  of  the  types  developed  during 
the  years  1916  and  1917. 

All  historical  matter,  in  fact,  everything  not  directly  relevant  to 
a  practical  understanding  of  a  wireless  telegraph  set,  should  be  sub- 
ordinated. The  call  at  this  period  is  for  men  trained  along  modern 
lines. 


MARCONI    INSTITUTE  19 

CONDUCTING  A  TECHNICAL  CLASS 

It  is  evident  that  students  who  come  from  all  walks  of  commercial 
and  private  life,  for  radio  instruction,  will  be  of  varying  grades  of  intel- 
ligence ;  hence  it  is  the  duty  of  the  instructor  in  charge  to  plan  out  a 
course  suitable  to  the  average  intelligence  of  each  class. 

A  course  outlined  for  one  set  of  students  will  not  necessarily  be 
applicable  to  the  next  or  succeeding  classes. 

A  good  method  to  pursue  in  a  class  of  different  degrees  of  prepara- 
tion, is  to  hold,  for  the  first  few  days,  general  "quiz"  questions.  These 
permit  the  instructor  to  determine  the  calibre  of  his  students  and 
enable  him  to  divide  them  into  two  groups. 

Group  ( 1 )  will  contain  those  who  have  some  knowledge  of  electricity 
and  magnetism,  and  perhaps  of  wireless  telegraphy. 

Group  (2)  will  consist  of  absolute  beginners. 

It  has  been  demonstrated,  notwithstanding  certain  students'  opposi- 
tion to  the  method,  that  the  student  graduate  who  has  been  well  trained 
in  the  basic  principles  of  the  art  progresses  most  rapidly  in  professional 
life. 

It  is  urged  that  wherever  possible,  instructors  teach  first  the 
fundamentals  and  then  show  the  student  the  deviations,  extensions  and 
refinements  of  these  principles  in  modern  practice.  The  student  will 
then  be  enabled  to  apply  his  general  knowledge  to  any  type  of  appa- 
ratus. 

When  the  technical  instruction  is  considered  complete,  the  student 
should  be  given  the  opportunity  to  manipulate  and  adjust  wireless  tele- 
graph apparatus.  He  should  be  supplied  with  a  wave  meter,  and 
through  the  medium  of  a  dummy  serial,  be  permitted  to  tune  the 
apparatus  to  resonance  at  the  standard  wave  lengths.  He  should  be 
taught  to  disassemble  and  re-assemble  a  wireless  telegraph  set,  and 
afterwards  to  place  it  in  first  class  working  order. 

All  instruction  of  this  nature  should  be  conducted  separately  from 
the  class  and  not  more  than  twelve  students  should  be  permitted  to 
enter  a  laboratory  at  one  time,  unless  a  large  equipment  and  a  con- 
siderable number  of  instructors  are  available  to  handle  the  work  in 
groups. 


20  MARCONI    INSTITUTE 

Intermediate  examinations  during  the  course  have  been  found  to  be 
of  considerable  value  for  they  offer  the  student  an  opportunity  to 
review  his  progress.  They  are  an  agreeable  change  from  the  every 
day  routine.  These  examinations  also  give  the  instructor  additional 
opportunity  to  judge  the  progress  of  the  student. 

The  best  results  are  secured  where  the  instructor,  from  time  to  time, 
performs  before  his  class  exceptionally  interesting  experiments. 

TEXT  BOOKS 

The  importance  of  an  authoritative  text  book  cannot  be  overesti- 
mated. A  daily  study  assignment  should  be  indicated  for  the  student, 
but  the  instructor  in  charge  must  select  only  such  material  as  will  be 
of  practical  use. 

One  of  the  best  methods  for  securing  rapid  progress,  especially  in 
a  mixed  class,  is  for  the  instructor  to  deliver  occasional  lectures  covering 
advanced  subjects.  When  in  daily  class  work  these  subjects  are  reached, 
the  student  will  immediately  recall  certain  facts  previously  brought  out 
by  the  lecturer,  which  will  obviously  facilitate  his  progress. 

BUZZER  CODE  PRACTICE 

The  Continental  Morse  Telegraph  code  (commonly  termed  the 
International  code)  is  universally  employed  in  wireless  telegraphy,  and 
radio  operators  generally  receive  their  training  on  a  buzzer  practice 
system  which  produces  artificial  radiotelegraphic  signals.  A  diagram 
of  such  a  circuit  appears  in  Figure  1,  where  a  number  of  head  tele- 
phones are  energized  by  a  single  buzzer. 


m-s 


Figure  1 


MARCONI    INSTITUTE 


21 


The  essentials  of  this  circuit  are,  a  battery  of  primary  cells  J5, 
a  telegraph  key  K,  a  buzzer  J5-1,  a  two-microfarad  condenser  C,  a  num- 
ber of  head  telephones  P-l,  P-2,  P-3,  etc. 

With  this  arrangement  the  condenser  C  is  periodically  charged  and 
discharged,  and  a  faithful  reproduction  of  the  note  of  the  vibrator  is 
secured  in  the  head  telephones.  If  there  are  less  than  one  hundred 
telephones  in  the  circuit,  it  will  be  necessary  to  shunt  the  telephone 
circuit  with  a  400-ohm  adjustable  rheostat  in  order  that  the  strength 


Figure  2 

of  the  signals  may  be  reduced  to  a  degree  consistent  with  everyday 
wireless  practice. 

The  student  at  each  position  at  the  code  practice  table  can  be 
supplied  with  a  telegraph  ke}^  which  is  connected  in  shunt  to  the  master 
key  through  the  leads  M-l,  Tlf-2,  and  thus  one  student  at  a  time  can 
transmit  to  the  remainder  of  the  class. 

Although  the  apparatus  described  is  much  used  for  code  iftstruction, 
difficulty  is  experienced  in  keeping  the  buzzer  in  constant  operation  and 


22  MARCONI    INSTITUTE 

in  consequence,  the  circuit  and  apparatus  shown  in  Figure  2,  is  strongly 
recommended. 

Here  a  small  motor  M  has  shunted  across  its  brushes  a  circuit 
consisting  of  the  condenser  C  of  two-microfarad  capacity,  head  tele- 
phones P-l,  P-2,  P-3,  etc.,  and  a  telegraph  key.  With  this  arrange- 
ment the  condenser  C  receives  a  fluctuating  charge,  and  if  the  motor 
rotates  at  a  high  speed,  say  1,800  to  2,400  R.P.M.,  a  faithful  reproduc- 
tion of  wireless  signals  will  be  obtained  with  the  great  advantage  that 
this  apparatus  will  work  day  in  and  day  out  without  trouble. 

The  type  of  motor  employed  is  immaterial,  whether  it  is  operated 
by  batteries  or  a  110-volt  direct  current  circuit,  but  it  is  of  considerable 
advantage  to  select  a  motor  the  brushes  of  which  are  mounted  on  a 
rocker  arm  so  they  can  be  shifted  through  a  small  arc.  In  this  way 
the  potential  across  the  condenser  can  be  increased  or  decreased  and 
the  strength  of  signals  varied  accordingly.  The  series-wound  motor 
has  been  found  to  give  the  best  results.  A  small  motor  operated  from 
an  8-volt  storage  battery  will  easily  actuate  from  three  to  four  hundred 
telephones,  and  if  a  number  of  shunt  circuits  with  special  condensers 
such  as  C-l,  C-2,  and  C-3  are  taken  off  the  brushes,  several  code  practice 
circuits  can  be  operated  without  interference  or  fluctuation  of  signals. 

DIVISION   OF   CLASSES 

It  is  recommended  that  code  instruction  classes  be  divided  as  follows : 

Group  1 — to  include  beginners  and  those  who  are  able  to 
receive  at  speeds  up  to  fire  words  per  minute. 

Group  2 — to  include  those  who  can  receive  at  speeds  from 
five  to  twelve  words  per  minute. 

Group  3 — to  include  those  capable  of  receiving  twelve  to 
eighteen  words  per  minute. 

Group  4 — to  include  those  capable  of  receiving  eighteen 
to  twenty-five  words  per  minute. 

For  the  first  day,  absolute  beginners  should  be  given  individual 
instruction ;  should  be  shown  how  to  hold  the  telegraph  key  and  how 
to  carefully  form  their  letters.  Their  work  should  be  closely  scruti- 
nized for  a  period  covering  from  three  to  five  days,  to  insure  the 
adoption  of  a  uniform  method  of  sending.  Thereafter,  they  can  be 


MARCONI    INSTITUTE  23 

placed  with  the  first  division  (Group  1)  and  progressively  advanced 
from  one  division  to  the  other  as  they  become  proficient.  When  the 
student  has  passed  the  five-word-per-minute  mark  the  instructor  should 
transmit  at  a  rate  slightly  in  excess  of  the  student's  ability.  This  will 
tend  to  hasten  the  student's  progress.  If  the  instructor  constantly 
transmits  only  at  a  speed  equal  to  the  ability  of  the  student  to  receive, 
it  is  not  likely  that  the  student  will  advance  rapidly. 

Should  the  expense  of  head  telephones  prove  prohibitive,  an  alterna- 
tive device  can  be  employed  for  code  instruction.  An  automobile  horn 
of  the  vibrator  type  operated  by  an  8-volt  storage  battery  may 
be  used  to  transmit  to  large  groups  of  students  at  a  time.  This  horn, 
mounted  on  the  wall,  can  easily  be  heard  throughout  a  large  classroom. 
It  has  been  employed  by  instructors  with  great  success  for  teaching 
elementary  students. 

The  procedure  for  training  elementary  students  follows : 

The  instructor  makes  a  particular  letter  of  the  telegraph  code  five 
or  six  times,  and  the  students  successively  call  out  the  letter  sounded. 
In  this  way  the  art  of  reception  is  quickly  learned. 


AUTOMATIC  TRANSMITTERS 

Automatic  transmitters  for  code  instruction  have  been  successful, 
the  particular  advantage  being  the  uniformity  of  sending  which  the 
student  unconsciously  imitates  and  adopts  in  his  own  transmitting. 
Among  the  prominent  automatic  transmitters  are  the  Wheatstone  and 
the  Omnigraph.  Most  practical  mechanical  code  instruction  can  be 
obtained  from  the  Marconi  Wireless  Telegraph  Records,  made  by  the 
Victor  Talking  Machine  Company.  These  records  are  described  on  the 
last  page  of  this  Manual. 

The  Wheatstone  automatic  transmitter  is  particularly  desirable  in 
addition  to  the  records,  but  it  necessitates  the  services  of  one  skilled 
in  tape  perforating. 

Special  types  of  Wheatstone  perforators  fitted  with  typewriter 
keyboards  are  now  available  and  by  a  little  practice  anyone  who  is 
capable  of  operating  a  typewriter  can  perforate  the  tapes.  Apparatus 
of  this  nature  is  costly,  and  is  to  be  considered  only  by  schools  which 
have  special  funds  available  for  the  purpose. 


24  MARCONI    INSTITUTE 

EQUIPMENT  FOR  TECHNICAL  TRAINING 

The  laboratory  of  an  advanced  radio  class  should  contain  a  modern 
500  cycle  quenched  spark  transmitter  of  the  type  used  by  commer- 
cial companies  and  the  Government.  This  equipment  should  include  a 
motor-generator,  starting  box,  receiving  tuner,  head  telephones,  and  a 
transmitting  key.  If  an  up-to-date  set  cannot  be  procured,  any  type 
of  apparatus  which  possesses  the  fundamental  parts  of  a  complete 
transmitter  and  receiver  will  serve  the  purpose. 

Owing  to  war  conditions  and  the  Government  regulation  of  the  sale 
of  wireless  apparatus,  laboratory  sets  are  difficult  to  procure,  but  the 
Marconi  Institute,  through  its  equipment  department,  will  endeavor,  if 
requested,  to  aid  in  securing  suitable  apparatus  for  schools  interested 
in  the  inauguration  of  a  wireless  telegraph  course. 


APPARATUS  FOR   CODE  INSTRUCTION 

As  explained  in  connection  with  the  diagram  of  Figure  2,  a  single 
high  speed  direct  current  motor  can  be  employed  to  operate  several 
hundred  head  telephones,  a  number  of  shunt  circuits  being  taken  there- 
from for  several  code  practice  divisions.  Practically  any  type  of 
direct  current  motor  can  be  employed  for  this  purpose. 

Assuming  a  class  of  one  hundred  pupils  the  necessary  electrical 
apparatus  would  be  as  follows : 

One  small  high-speed  D.  C.  motor,  100  head  telephones,  50  trans- 
mitting keys,  1  2-microfarad  condenser,  200  binding  posts,  wire  for 
connections. 

Assuming  that,  instead  of  a  motor  a  buzzer  equipment  is  employed, 
there  should  be  at  least  one  buzzer  to  each  twenty-five  students.  The 
necessary  apparatus  for  each  group  of  twenty-five  follows : 

One  4-volt  buzzer,  25  telephones,  12  transmitting  keys,  50  binding 
posts,  1  2-microfarad  condenser. 

For  a  school  with  limited  funds  an  automobile  horn  of  the  vibrator 
type  will  prove  satisfactory,  but  it  will  be  necessary  to  separate  the 
several  classes  in  partitioned  rooms  so  that  the  sounds  of  several  horns 
will  not  interfere. 


MARCONI    INSTITUTE  25 

DIVISION  OF  THE  DAILY  ROUTINE 

The  day  class  for  instruction  in  theory  and  code  practice  should 
convene  at  10  A.M.  until  12  noon,  and  from  1  to  4.30  P.M.  Schools 
giving  instruction  in  military  tactics  in  addition  to  radio  will,  of  course, 
lengthen  their  hours.  A  technical  class  session  should  be  conducted 
from  10  A.M.  to  11  A.M.  and  laboratory  experiments  from  11  to  12  M. 
Code  instruction  should  be  given  from  1  to  4.30  P.M.,  with  brief 
intermissions  to  afford  students  a  respite. 

It  is  customary  in  the  classes  of  the  Marconi  Institute  to  include, 
once  per  week,  a  half  hour  or  an  hour  lecture  on  radio  traffic,  but  if 
such  instruction  is  not  required,  the  student  should  be  shown,  for 
instance,  the  geographical  locations  of  prominent  radio  stations 
throughout  the  world.  Such  instruction  will  serve  to  renew  interest 
and  to  destroy  the  dullness  of  daily  routine. 

QUALIFICATIONS  OF   STUDENTS 

IN  response  to  the  appeal  of  the  Federal  Board  for  Vocational  Edu- 
cation, for  schools  to  undertake  the  training  of  drafted  men  in  radio 
code  and  buzzer  practice  previous  to  their  assignments  to  cantonments, 
a  great  number  of  universities,  colleges,  public  schools,  and  high  schools 
will  establish  special  classes. 

One  of  the  first  matters  to  be  given  attention  is  the  qualifications 
of  the  applicant  for  admittance.  Schools  devoted  primarily  to  training 
selected  men  under  the  plan  of  the  Federal  Board  for  Vocational  Educa- 
tion, should  accept  none  but  those  due  for  the  second  and  following 
drafts  and  who  can  pass  the  required  Government  physical  examination. 

If  the  selected  man  has  not  yet  been  examined  physically  by  his 
Examining  Board,  arrangements  should  be  made  with  a  local  physician 
to  do  this  work  gratis.  He  should  pass  generally  on  the  applicant's 
fitness  for  admittance  to  the  Government  Service. 

Instructors  of  such  classes  should  make  every  effort  at  the  very 
start  to  weed  out  all  men  who  do  not  possess  the  requisite  education 
or  other  qualifications  for  the  Government  Service. 

Schools  to  train  men  particularly  for  Government  Service  should 
exclude  girls  and  women;  persons  under  military  age;  persons  not 
conscripted ;  persons  conscripted  but  unable  to  pass  the  physical  exam- 
ination; persons  exempted  for  any  cause;  and  persons  who  are  seeking 
only  free  training  for  commercial  service. 


26  MARCONI   INSTITUTE 

It  is  evident  that  applicants  for  admission  to  these  classes  will  be 
of  mixed  grades  of  intelligence.  Consequently  the  instructors  in  charge 
should  make  every  effort  to  segregate  and  apportion  the  men  to  proper 
classes  directly  upon  entrance.  There  will  be  a  constant  change  in 
students'  personnel  and  it  will  be  necessary  to  arrange  the  curriculum 
accordingly. 

TIME  REQUIRED  FOR  CODE  TRAINING 

On  an  average  it  requires  two  hundred  hours  to  train  a  first-class 
radiotelegraphist  in  code  work,  exclusive  of  technical  instruction.  As- 
sume that  a  code  class  convenes  for  six  sessions  per  week  and  that  two 
hours  per  session  be  devoted  to  code  practice,  it  will  require  from  twelve 
to  fourteen  weeks  to  qualify  an  absolute  beginner  to  pass  a  code  test  of 
twenty  words  per  minute. 

If  the  student  is  also  to  be  taught  technical  wireless  telegraphy,  it 
will  lengthen  the  course  by  about  six  weeks.  Technical  instruction 
during  two  sessions  per  week  will  be  ample. 

Obviously,  greater  difficulty  will  be  experienced  in  dividing  classes 
for  technical  instruction  than  for  code  instruction,  but  the  instructor 
should  have  no  difficulty  in  directing  two  classes  simultaneously — one 
of  beginners  and  one  for  more  advanced  students. 

OBTAINING  STUDENTS 

A  list  of  conscripted  men  in  each  community  can  be  secured  from 
the  local  Examination  Board  or  from  the  files  of  local  newspapers. 
A  circular  should  be  sent  to  these  conscripted  men  by  the  school  authori- 
ties, asking  them  to  appear  for  registration  for  the  course.  The 
circular  should  furnish  all  necessary  information  as  to  what  it  is  pro- 
posed to  offer  them.  Every  effort  should  be  made  to  obtain  publicity 
through  local  newspapers  and  local  commercial  and  civic  organizations. 

INSTRUCTORS 

Instructors  for  code  classes  can  be  obtained  from  among  retired 
wireless  operators  or  from  commercial  or  railway  telegraphists. 
Similarly,  technical  instructors  can  be  secured  from  among  retired 
wireless  operators  or  those  who  have  had  active  training  in  universities 
or  colleges.  The  Marconi  Institute  has  on  file  a  list  of  men  available 


MARCONI    INSTITUTE  27 

for  such  services,  and  will  endeavor  to  supply  qualified  instructors  in 
any  locality.  Code  instructors  are  paid  from  $3.00  to  $5.00  per  eve- 
ning and  technical  instructors  $4.00  to  $8.00  per  evening. 

RECORDS 

The  records  to  be  kept  in  the  school  are  similar  to  those  of  any 
educational  institution,  but  care  should  be  taken  to  have  them  accurate 
in  every  respect,  so  that  the  Federal  Board  can  supply  the  United 
States  Army  with  complete  information  regarding  the  number  of 
students  attending.  Blanks  will  be  sent  by  the  Federal  Board  to  train- 
ing institutions,  from  time  to  time,  upon  which  this  information  can 
be  recorded. 

OPPORTUNITIES  IN  THE  MILITARY  SERVICE 

Naturally,  conscripted  men  will  want  to  know  just  what  opportuni- 
ties for  advancement  the  Government  has  provided  in  event  of  their 
joining  a  local  radio  telegraph  school.  It  can  be  stated  authoritatively 
that  the  immediate  need  of  the  Army  is  fifteen  thousand  (15,000)  radio 
and  buzzer  operators.  Those  possessing  a  considerable  knowledge  of 
radio  telegraphy  and  assigned  to  cantonments  will  be  in  line  for  more 
rapid  advancement  in  the  Signal  Corps.  The  greater  their  skill,  the 
higher  the  appointment  they  will  obtain. 

Although  assigned  to  a  cantonment  as  a  private,  the  drafted 
man,  if  selected  as  a  radio  or  buzzer  operator  after  the  vocational 
census  is  taken,  may  advance  to  the  rank  of  corporal,  or  sergeant, 
at  a  wage  of  from  $36  to  $51  monthly.  If  he  has  unusual  qualifications 
and  obtains  rapid  promotion  in  the  cantonment,  he  may  secure  the 
position  of  master  signal  electrician  with  a  wage  of  $81  per  month. 

Arrangements  are  now  under  way  whereby  the  Signal  Corps  will 
give  the  student  advanced  instruction  in  the  cantonment  if  he  is  unable 
to  complete  his  course  at  a  regular  school.  Promising  young  men  who 
have  shown  ability  in  ordinary  training  schools  will  be  eligible  for  selec- 
tion for  this  special  instruction. 

DAY  AND  EVENING  CLASSES 

It  is  certain  that  an  evening  class  will  attract  more  students  than^- 
day  class,  because  the  man  subject  to  conscription,  if  employed, '  wilP  •* 

hold   his   position   up   to   the   time   he   is    assigned   to    a    cantonn^ent.'A7" 

c  .TV  j.  v  J£  R  s  1 3 

^  S*j 


28 


MARCONI    INSTITUTE 


Evening  classes  should  convene  not  earlier  than  7:30  P.M.  and 
continue  no  longer  than  two  and  a  half  hours.  It  has  been  the  experi- 
ence of  evening  schools,  backed  by  statistics,  that  longer  evening 
sessions  militate  against  efficiency  rather  than  contribute  to  the  stu- 
dent's progress. 

It  may  be  desirable  in  certain  localities  to  hold  classes  convening 
from  5  :00  P.M.  to  7  :30  P.M.  to  accommodate  those  who  live  far  from 
schools  and  are  unable,  at  the  close  of  a  day's  work,  to  go  home  for 
supper  and  return  to  their  classes. 

The  exact  hours  of  an  evening  school  should  be  adapted  to  the 
distance  of  travel  and  transportation  facilities  in  a  given  localitv. 


A  typical  transmitting  and  receiving-  set  of  the  type  installed  on  ships  under 
the  U.  S.  Flag  during  the  years  1907  to  1912.  The  photograph  shows  part  of  the 
transmitting  apparatus,  the  receiving  tuner,  the  aerial  changeover  switch,  and  a 
small  induction  coil  auxiliary  set. 


COURSES  OF  INSTRUCTION  AT  THE  MARCONI  INSTITUTE 

HpHE  Marconi  Institute  was  established  in  the  year  1909,  to  train 
•^  commercial  wireless  operators  for  ship  and  shore  station  service. 
The  scope  of  this  institution  has  gradually  been  extended  to  include 
more  advanced  work,  to  fit  men  to  become  radio  inspectors,  construction 
engineers,  radio  experts  and  experimental  engineers. 

Since  America  entered  the  war  the  doors  of  the  Institute  have  been 
thrown  open  for  training  men  in  radio  for  all  departments  of  the 
Government,  in  addition  to  the  merchant  marine  service. 

The  Institute  has  already  prepared  many  men  for  the  aviation 
reserve,  signal  corps  reserve,  the  artillery,  enlisted  naval  men  and 
men  in  similar  service.  The  course  of  instruction  has  been  especially 
adapted  to  meet  the  needs  of  the  Federal  service. 

The  Marconi  Institute  is  equipped  with  an  exceptionally  complete 
outfit  of  wireless  apparatus.  By  reason  of  its  experience  and  equip- 
ment, it  possesses  unusual  facilities  for  training  advanced  radio  tele- 
graphists for  national  and  commercial  service. 

In  addition  to  personal  instruction  given  in  classes,  the  Institute 
provides  a  complete  and  systematic  course  of  training  by  means  of 
text  books,  code  practice  apparatus,  printed  outline  lectures  and  writ- 
ten examinations,  which  constitute  a  complete  home  study  or  reading 
course  for  those  who  are  unable  to  attend  proper  training  schools. 
It  has  selected  and  made  available  for  individual  study  such  wireless 
literature  as  is  best  adapted  for  instruction  along  modern  lines.  Not 
only  has  this  Institute  trained  men  for  the  particular  services  men- 
tioned; it  has  also  provided  instruction  for  engineers  from  foreign 
countries,  to  fit  them  to  undertake  and  maintain  important  installations 
in  their  home  lands. 

CLASSES  or  THE  INSTITUTE 

The  classes  of  the  Marconi  Institute  are  conducted  at  the  follow- 
ing places :  Headquarters — Edison  Building,  corner  Elm  and  Duane 
Streets,  New  York  City;  Branches — Cleveland,  Ohio,  Rooms  361-70 
Lenox  Building,  Euclid  Avenue  and  East  9th  Street;  San  Francisco, 
Cal.,  New  Call  Building,  New  Montgomery  Street. 

29 


30 


MARCONI    INSTITUTE 


Front  View  Back   View 

MARCONI    i/2    K.W.    500    CYCLE    TRANSMITTER 

On  certain  vessels,  a  transmitter  of  2  K.W.  capacity  is  not  required.  Hence 
a  special  %  K.W.  transmitter  was  developed  by  the  American  Marconi  Company 
for  ship  service.  The  photograph  shows  one  of  the  latest  types  of  panel  sets  of 
this  power  which  in  general  is  similar  to  the  2  K.W.  500  cycle  set.  The  motor- 
generator  is  fitted  with  a  special  type  of  automatic  starter  and  both  the  quenched 
and  rotary  spark  discharges  are  employed.  The  apparatus  is  also  constructed 
for  rapid  change  of  wave  length,  the  standard  waves  of  300,  450  and  600  meters 
being  provided  for. 


MARCONI  INSTITUTE  31 

HOUES 

Both  day  and  evening  sessions  are  held. 

The  hours  of  the  day  class  are  from  10  A.M.  to  12  noon  and  from 
1  P.M.  to  4:30  P.M.,  Saturdays  from  9:30  A.M.  to  12  noon.  The 
evening  classes  hold  sessions  from  7 :30  P.M.  to  9 :45  P.M.,  Monday  to 
Friday,  inclusive. 

There  will  be  established  a  third  class,  to  convene  at  3 :30  P.M.  and 
close  at  7  P.M.  This  will  provide  instruction  for  men  who  are  unable 
to  attend  at  other  hours  during  the  day. 

Under  the  present  arrangement,  technical  instruction  in  the  day 
class  is  given  from  10  A.M.  to  12  noon  Monday  to  Friday ;  code  instruc- 
tion from  1  P.M.  to  4  :30  P.M.  Monday  to  Friday,  and  Saturday  from 
9:30  A.M.  to  12  noon,  with  the  exception  of  a  half-hour  traffic  class 
which  is  held  on  Wednesday  from  3 :30  P.M.  to  4  P.M. 

In  the  evening  class  technical  instruction  is  given  Monday  and 
Thursday  from  7 :30  to  9  :45  P.M.  Tuesday,  Wednesday  and  Friday 
are  devoted  to  code  and  traffic  instruction. 

The  Institute  is  closed  on  holidays. 

QUALIFICATIONS  OF  APPLICANT. 

An  applicant  for  admission  to  the  classes  at  the  Marconi  Institute 
must  qualify  as  follows : 

(1)  He  must  not  be  less  than  sixteen  years  of  age. 

(2)  //  he  intends  to  enter  the  commercial  or  Government 
service  he  must  be  a  citizen  of  the  United  States. 

(3)  He  must  possess  at  least  a  grammar  school  education. 

(4)  He  must  furnish  satisfactory  references. 

(5)  He  must  possess  a  birth  certificate. 

(6)  //  he  has  taken  out  naturalization  papers  he  must 
present  them  for  inspection. 

TELEGEAPH  CODES  AND  PEACTICE 

Only  the  Continental  Morse  code  is  used  in  radio,  but  special  instruc- 
tion will  be  given  in  the  American  Morse  code  to  those  desiring  it. 
The  classroom  is  fitted  with  head  telephones  and  apparatus  which  give 
a  perfect  reproduction  of  wireless  telegraph  signals.  The  operator's 
tables  are  so  connected  that  the  instructor  in  charge  can  send  to  the 


32 


MARCONI   INSTITUTE 


FRONT   VIEW 

These  photographs  show  the  front  and  rear  view  of  the  2  K.W.  500  cycle  trans- 
mitter developed  by  the  Marconi  Wireless  Telegraph  Company  of  America.  This 
transmitter  is  designed  for  three  standard  wave  lengths — 300,  450  and  600  meters 
• — and  is  fitted  with  a  special  multiple  point  radio  frequency  switch  whereby  the  wave 
length  can  be  instantly  changed  from  one  to  the  other  by  the  operation  of  a  single 


MARCONI   INSTITUTE 


33 


BACK  VIEW 

switch  handle.  The  transmitter  is  supplied  with  both  quenched  and  rotary  spark 
dischargers,  and  the  motor  generator  is  fitted  with  an  automatic  motor  starter  for 
distant  control.  These  sets  have  a  daylight  range  of  500  to  600  miles  and  a  night 
range  up  to  2,500  miles.  The  actual  range  of  the  transmitter,  of  course,  varies 
with  the  type  of  oscillation  detector  employed  at  the  receiving  station.  Hundreds 
of  these  transmitters  are  in  daily  use. 


34  MARCONI   INSTITUTE 

entire  class  simultaneously,  or  the  class  may  be  divided  into  sections, 
each  section  obtaining  separate  instruction. 

The  students'  tables  are  equipped  with  transmitting  keys  enabling 
them  to  communicate  with  one  another. 

Call  letters  of  prominent  ship  and  shore  stations  are  assigned  to  the 
various  tables  and  traffic  is  dispatched  after  the  method  employed 
at  commercial  stations. 

In  addition,  a  Wheatstone  automatic  transmitter  is  in  daily  use. 
By  means  of  this  device  messages  which  have  previously  been  perforated 
on  tape  are  automatically  sent  to  the  class  at  any  desired  speed.  This 
apparatus  is  a  duplicate  of  that  employed  at  the  high  power  trans- 
mitting stations  for  sending  press  and  commercial  messages  to  ships. 

RADIO  TRAFFIC 

One  of  the  special  features  of  the  Marconi  Institute  is  its  class 
devoted  to  instruction  in  the  dispatch  of  wireless  traffic.  In  times  of 
peace,  when  trade  routes  and  business  are  normal,  correct  methods  of 
routing  and  handling  traffic  are  highly  important.  The  students  of  the 
Institute  are  taught  not  only  the  method  of  procedure  in  the  dispatch 
of  all  kinds  of  traffic  from  ship  to  ship  and  from  ship  to  shore,  but 
they  are  given  thorough  training  in  accounting  for  tolls,  the  making 
up  of  final  abstract,  the  trade  routes  of  different  steamship  lines,  and 
the  special  problems  which  the  operator  encounters  in  the  transmission 
of  messages  through  foreign  stations.  The  instructors  in  this  depart- 
ment are  specially  qualified  through  years  of  practical  experience  in 
actual  service  throughout  the  world. 

Students  are  taught  thoroughly  the  Regulations  of  the  Interna- 
tional, Telegraphic  Convention,  and  also  the  special  Regulations  issued 
by  the  Bureau  of  Navigation  or  the  Naval  Communication  Service. 

LABORATORY  EQUIPMENT 

The  Institute  is  supplied  with  the  most  advanced  types  of  wireless 
telegraph  apparatus  developed  by  commercial  wireless  companies.  The 
equipment  consists,  in  part,  of : 


MARCONI    INSTITUTE  35 

(1)  A  2-K.W.,  500  cycle  quenched  gap  panel  transmitting 
set  of  the  latest  type,  with  all  accessory  apparatus  for  its 
commercial  operation. 

(2)  A  standard  l/2-K.W.,  500  cycle  transmitting  set  of 
the  latest  type. 

(3)  A  y^-K.W.,  500  cycle  cargo  type  transmitting  appa- 
ratus. 

(4)  A  2-K.W.  240  cycle  disc  discharger  transmitting  set. 

(5)  A  l-K.W.  non-synchronous  rotary  transmitting  set 
with  switch-board  and  all  auxiliary  appliances. 

(6)  Standard  auxiliary  or  emergency  transmitter  for  use 
on  ships. 

(7)  A  complete  storage  battery  installation  with  switch- 
boards and  all  accessory  apparatus  for  instruction  in  the 
maintenance  and  care  of  storage  cells. 

(8)  Several  of  the  latest  types  of  receiving  tuners  em- 
ployed in  commercial  service. 

(9)  A  Marconi  Direction  Finder  Set  complete. 

(10)  Numerous   types   of  wavemeters,   decremeters,   and 
special  parts  of  both  transmitting  and  receiving  apparatus 
for  class  instruction. 

Experimental  apparatus  is  constructed  by  students  as  part  of 
their  course.  Students  who  show  special  ability  in  conducting  experi- 
ments are  encouraged  to  make  further  investigations  into  radio  tele- 
graphic measurements,  thereby  fitting  themselves  for  advanced  work. 

THE  TECHNICAL  COURSE 

The  Institute's  technical  instruction  begins  with  elementary  prin- 
ciples of  electricity  and  magnetism  and  continues  through  every  de- 
partment of  electrical  practice  up  to  the  radio  frequency  circuits  of 
wireless  telegraphy.  The  subjects  treated  are  outlined  in  their  order 
on  page  17. 

The  Institute  is  under  the  supervision  of  men  with  years  of  practical 
and  theoretical  experience.  Consequently,  the  instruction  provided 
equips  the  student  to  take  his  place  i»  the  front  ranks  of  commercial 
wireless, 


MARCONI    INSTITUTE 


The  desirability  of  panel  types  of  transmitters  was  early  recognized  in  the 
art.  The  photograph  shows  the  special  y2  K.  W.  120  cycle  transmitting  set  de- 
signed by  the  American  Marconi  Company.  This  apparatus  is  complete  in  every 
respect  and  is  supplied  with  both  the  quenched  multiple  plate  and  rotary  spark 
discharger.  The  additional  apparatus  required  to  make  a  complete  transmitting 
and  receiving  system  is  the  receiving  tuner,  antenna  changeover  switch,  and  a 
telegraph  key.  Transmitters  of  this  type  are  employed  as  the  main  power  sets 
for  cargo  vessels  or  as  an  auxiliary  set  on  vessels  carrying  transmitting  apparatus 
of  greater  power. 


MARCONI    INSTITUTE  37 

Those  who  contemplate  entering  the  service  of  a  commercial  com- 
pany should  not  overlook  this  essential  feature. 

The  Institute  offers  training,  based  on  commercial  practice  in  the 
years  1917  and  1918,  through  which  the  graduate  is  qualified  to  meet 
the  requirements  of  present  day  practice.  The  latest  developments 
in  wireless  telegraphy  are  taught,  in  advance  of  the  general  dissemina- 
tion of  this  information  to  the  public.  The  Institute's  relations  with 
large  commercial  companies  enable  it  to  offer  instruction  not  available 
in  other  schools. 

TIME  REQUIRED 

The  time  required  for  the  complete  course  depends  largely  upon 
the  capability  of  the  student.  Generally  speaking,  the  completion  of 
a  technical  course  requires  two  and  a  half  months'  daily  instruction. 
The  time  required  to  complete  the  code  course  cannot  be  accurately 
estimated  in  advance.  If  the  applicant  is  able  to  receive  at  a  speed  of 
ten  words  per  minute  at  entrance,  he  should  be  qualified  to  pass  the 
Government  license  examination  at  the  end  of  two  months.  An  absolute 
beginner  will  require  from  three  to  three  and  a  half  months  code 
instruction. 

The  time  required  to  qualify  in  the  evening  class  is  somewhat  in 
excess  of  this ;  usually  from  four  to  five  months  in  code  instruction  and 
from  two  and  a  half  to  three  and  a  half  nfonths  technical  instruction. 
The  Marconi  Institute  arranges  the  course  for  each  new  class,  to  suit 
the  capabilities  of  the  enrolled  students. 

An  intensive  training  course  is  provided  for  those  with  special 
qualifications;  this  course  is  completed  in  six  weeks. 

EXAMINATION 

The  final  examinations  of  the  Marconi  Institute  are  suited  to  the 
particular  branch  of  radio  telegraphy  which  the  student  desires  to 
enter.  In  the  technical  examination  a  passing  mark  of  75  per  cent. 
is  required  and  in  the  examination  covering  radio  traffic  a  rating  of  not 
less  than  80  per  cent,  is  required.  At  the  completion  of  the  course  a 
certificate  is  issued  to  the  students  upon  which  is  recorded  the  number 
of  hours  he  has  attended,  his  rating  both  in  the  theory  of  radio  and 
radio  traffic,  and  his  knowledge  of  American  Morse  and  Continental 
telegraph  codes. 

(Graduates  of  the  code  division  must  be  able  to  transmit  and  receive 


38  MARCONI    INSTITUTE 

at  a  speed  of  twenty  words  a  minute  in  the  Continental  Morse  telegraph 
code. 

GOVERNMENT  EXAMINATION  FOR  OPERATORS'  LICENSES 

Commercial  radio  telegraphists  must  secure  Government  license 
certificates  before  they  can  be  employed  as  wireless  operators.  Oper- 
ators examinations  are  held  at  custom  houses  and  navy  yards  through- 
out the  United  States.  To  inform  applicants  of  the  gradations  of 
commercial  wireless  licenses  and  the  qualifications  expected  from  the 
students  undergoing  the  examinations,  the  following  general  outline 
is  appended. 


The  introduction  of  the  Magnetic  Detector  by 
Marconi  marked  a  step  in  the  progress  of  commer- 
cial wireless  telegraphy,  for  it  permitted  the  use 
of  a  telephone  as  a  current  translator.  Two  ad- 
vantages were  thus  derived:  the  receiving  operator 
was  enabled  to  distinguish  between  the  interfering 
signals  caused  by  the  discharges  of  atmospheric 
electricity  and  those  sent  out  by  the  transmitting 
station.  Beyond  this  the  telephone  permitted  a 
much  higher  speed  of  transmission  and  reception 
than  the  coherer. 

The  photograph  shows  the  Magnetic  Detector 
and  its  receiving  tuner  known  as  the  Multiple 
Tuner,  which  has  a  range  of  wave  length  from  80 
to  2,600  meters.  With  this  apparatus  signals  are 
received  aboard  ship,  in  mid-ocean  from  the  Mar- 
coni High  Power  stations  at  Cape  Cod,  Massachu- 
setts, U.  S.  A.,  and  at  Poldhu,  Cornwall  in  England. 


MARCONI    INSTITUTE 


39 


GRADATION   OF   COMMERCIAL   OPERATORS'   LICENSES 

GRADE  SPEED     REQUIRED       TECHNICAL  EXAM. 

(   30    words    per    minute    (    , 

Ameriran  Mnr<^  Wider  in  scope  than  ex- 

amination for  original 
first  grade  certificate. 
(Passing  mark  80%). 


Commercial    |        American  Morse. 
Extra   1st  \    25    words    per    minute 
Grade  ----  International  or  Con- 

tinental  Code. 


Commercial 
1st  Grade 


Second 
Grade 


Cargo 
Grade 


20  words  per  minute 
Continental  Code  (5 
letters  per  word). 


12  words  per  minute 
Continental  Code  (5 
letters  per  word). 

Approximately  5  words 
per  minute  Continen- 
tal Code.  (Sufficient  to 
enable  "watcher"  to 
interpret  SOS  sig- 
nals and  call  letters.) 


(a)  Adjustment,  opera- 
tion and  care  of  com- 
mercial apparatus. 

(b)  Correction  of  faults. 

(c)  Use    and    care    of 
storage  batteries  and 
auxiliary  apparatus. 

Same  as  examination 
for  first  grade  but 
lessened  scope. 

Must  be  able  to  explain 
adjustment  of  receiv- 
ing apparatus  and 
draw  simple  funda- 
mental wiring  dia- 
gram of  transmitter 
and  receiver. 


CREDITING  OF  GOVERNMENT  LICENSE 

(75%  constitutes  passing  mark  for  first  grade  certificate;  65%   for 

second   grade   certificate).  Points 

Awarded. 
A — Experience 20 

B— Diagram  of  Transmitting  and  Receiving  Apparatus 10 

C — Knowledge  of  Transmitting  Apparatus    20 

D— Knowledge  of  Receiving  Apparatus 20 

E — Knowledge  of  the  Operation  and  Care  of  Storage  Batteries  10 

F— Knowledge  of  Motors  and  Generators 10 

G — Knowledge    of    the    International    Regulations    Governing 
Radio    Communication    and    the    U.    S.    Radio    Laws    and 

Regulations    10 

FOR  STUDENTS  FROM  OUT  OF  TOWN 

Young  men  from  outlying  cities  may  secure  board  and  rooms  at 
the  Y.  M.  C.  A.'s  in  Greater  New  York.  Certain  of  these  institutions 
have  licensed  employment  bureaus  which  can  frequently  place  students 
in  day  or  evening  positions,  helping  them  to  defray  expenses  while 
attending  school.  Good  board  and  room  can  be  secured  in  New  York 
City  at  from  $7.50  to  $10.00  per  week. 

The  Marconi  Institute  does  not  secure  boarding  places  for  its 
students,  but  has  on  file  a  list  of  places  where  the  young  men  can  be 
quartered  during  their  period  of  instruction. 


MARCONI    INSTITUTE 


A  special  type  of  receiving  apparatus  was  devised  in  the 
year  1907  to  1908  for  use  of  both  ship  and  shore  stations. 
The  photograph  shows  a  type  of  inductively  coupled  re- 
ceiver employed  in  ship  installations  under  the  United 
States. Flag  during  the  years  1908  to  1912.  It  is  a  complete 
receiving  set  constructed  specially  for  use  with  the  car- 
borundum detector.  The  tuning  apparatus  consists  of  an 
inductively  coupled  receiving  transformer,  primary  and  sec- 
ondary condensers,  potentiometer,  battery,  and  detector 
holder.  It  possesses  a  range  of  wave  length  from  200  to 
:?,000  meters. 


Dr.  J.  Ambrose  Fleming,  of  London,  England,  devised  a 
very  effective  oscillation  detector  which  he  named  the  Oscilla- 
tion Valve.  He  discovered  that  the  electrons  thrown  off  by  the 
incandescent  filament  could  be  made  to  rectify  the  extremely 
high  frequency  oscillations  employed  in  wireless  telegraphy, 
changing  them  into  minute  pulsating  direct  currents  suitable 
for  operation  of  the  head  telephone.  Also,  on  account  of  their 
mobility,  these  electrons  permitted  a  very  precise  relaying 
action  much  similar  to  that  obtained  from  a  telegraph  key. 

The  receiving  tuner  shown  in  the  photograph  was  specially 
designed  for  use  with  the  Fleming  Oscillation  Valve.  It  has  a 
range  of  wave  length  from  300  to  1,650  meters  and  is  widely 
used  in  ship  installations. 


MARCONI    INSTITUTE  41 

THE  INSTITUTE  EXTENSION  COURSE 

'IpHE  Marconi  Institute  Extension  Training  Course  and  Service  is  a 
•••  systematic,  time-saving  means  of  furnishing  to  students  in  the  war 
camps,   homes    or   local   radio    clubs,    orderly    and    scientific    training 
through  literature  prepared  by  the  leading  exponents  of  the  art. 

It  is  indispensable  to  experimenters  or  students  who  desire  a  thor- 
ough working  knowledge  of  wireless.  This  service  already  has  been 
subscribed  to  by  8,000  men. 

It  is  planned  primarily  for  those  who  are  progressive  and  alert  and 
who  look  ahead  to  the  future. 

Wonderful  expansion  in  every  department  of  scientific  development 
and  industrial  application  is  assured.  Students  and  experimenters  who 
use  the  opportunities  presented  to  them  through  the  Institute  Exten- 
sion Course  and  Service,  will  never  regret  the  time  given  to  such  study. 

It  is  not  essential  that  students  have  a  college  or  technical  educa- 
tion, but  one  thing  is  necessary :  they  must  have  a  serious  purpose  and 
be  willing  to  devote  a  reasonable  portion  of  their  spare  time  to  study 
and  practice. 

THE  ORGANIZATION 

The  Extension  Training  Course  and  Service  is  directed  by  success- 
ful business  men  and  recognized  expert  instructors. 

PERSONS  BENEFITED 

It  brings  to  the  student  essential  and  reliable  data  that  is  not  other- 
wise available  in  convenient  form  and  at  reasonable  cost.  It  presents 
the  best  thought  of  the  leaders  in  wireless  work  in  America.  It  covers 
the  essential  subjects  of  which  every  radio  student  should  be  informed. 

This  Extension  Service  is  designed  especially  for: 

(1)  Persons  who  are  already  engaged  in  commercial  and 
government  wireless  work. 

(2)  Students  and  experimenters  who  are  looking  forward 
to  entering  either  commercial  or  military  service. 

(3)  Individuals  and  the  membership  of  local  wireless  asso- 
ciations attracted  to  the  experimental  wireless  field  by  the 
fascination  of  the  radio  art. 

(4)  Instructors  engaged  in  conducting  radio  classes. 

The  Institute  Service  in  outline : 

(1)   It  furnishes  the  subscriber,  in  the  pages  of  THE 
WIRELESS   AGE   (the   official  monthly   magazine  of   the 


42  MARCONI    INSTITUTE 

Institute)  and  in  specially  prepared  text  books,  a  most  com- 
plete and  probably  the  best  organized  treatment  of  wireless 
principles  and  practice  available  for  individual  study. 

(2)  It  guides  and  stimulates  the  reading  of  the  texts  by  a 
series  of  outline  suggestive  studies. 

(3)  It  keeps  the  student  in  touch  with  the  best  current 
thought  and  practice  through  special  periodic  wireless  exten- 
sion lectures. 

(4)  It  offers  him  opportunities  for  applying  his  knowledge 
in  commercial  service  and  prepares  him  to  enter  government 
service. 

(5)  It  answers  all  personal  inquiries  in  connection  with  his 
training  course. 

To  help  meet  the  immense  demand  for  trained  men  for  the  National 
Service,  and  to  replace  those  called  from  the  ranks  of  mercantile  life, 
the  Institute  now  provides  in  the  pages  of  The  Wireless  Age  a  series  of 
Extension  Training  Courses  in  the  following  branches,  of  which  there 
is  urgent  need.  The  subjects  treated  are  listed  under  each  course. 
AVIATION — Conducted  by  Henry  Woodhouse,  Governor  of  the  Aero 
Club  of  America. 

Principles  and  theory  of  flight — nomenclature,  assembly,  rigging — 
care  and  repair  of  aeroplanes — operation  and  care  of  aeronautical  engines 
— principles  of  general  and  cross-country  flying — reconnaissance,  map 
reading,  signaling  and  co-operation  with  military  bodies — radio  for  air- 
craft and  its  uses — machine  gunnery  and  bombing  from  aeroplanes. 

SIGNAL  CORPS  WORK — Conducted  by  Major  J.  Andrew  White,  Chief 
Signal  Officer,  Junior  American  Guard. 

Function  and  operations  of  the  Signal  Corps  and  its  relation  to  the 
line  of  the  army — drill  instruction,  mounted  and  dismounted,  for  telegraph 
companies,  radio  and  outpost  companies,  and  battalions  of  Signal  Corps 
— signaling  by  telegraph,  heliograph,  night  lantern  and  flags,  radio  and 
service  buzzer — camp  and  field  telephones  and  their  uses — radio  apparatus 
of  the  Signal  Corps — scouting,  patrolling  and  tactical  employment  of 
field  lines. 

WIRELESS  TELEGRAPHY — Conducted  by  Elmer  E.   Bucher,  Direc- 
tor of  Instruction,  Marconi  Institute. 

Code  practise — elementary  electricity  and  magnetism — primary  and 
secondary  batteries — electrical  units  and  circuits — electromagnetism — 
electromagnetic  induction — the  dynamo,  motor  and  motor-generator — 
transmitting  and  receiving  apparatus — transformers — tuning — modern 
wireless  sets — measurements — undamped  oscillation  transmitters  and  re- 
ceivers— regenerative  receiving  circuits. 

NAVIGATION — Conducted  by  Capt.  F.  E.  Uttmark,  Principal,  Utt- 
mark's  Nautical  Academy. 

Compass  work — details  of  Mercator's  chart — coastwise  and  ocean 
chart  sailing — keeping  the  log  book — the  taffrail  and  chip  logs — dead 
reckoning — care  and  use  of  the  sextant  and  chronometer — correcting 


MARCONI    INSTITUTE  43 

altitudes  and  declination — latitude  by  meridian  observation  of  the  sun — 
selection  and  use  of  logarithms — various  kinds  of  time — longtitude  by 
solar  sights — deviation  of  compass  by  sun  azimuths,  and  by  terrestrial 
ranges. 

These  courses  are  conducted  exactly  as  lecturers  give  them  to  their 
classes. 

The  printed  diagrams  and  charts  take  the  place  of  regular  black- 
board exercises,  and  the  text,  covering  description,  principles  and  appli- 
cation, progresses  step  by  step  through  elementary  instruction,  appa- 
ratus and  practical  operation. 

The  cost  of  similar  instruction  in  regular  training  schools  would  be: 

Aviation $75 

Signal  Corps  Work 75 

Wireless  Telegraphy 65 

Navigation     100 

Total   $315 

Furnished  in  The  Wireless  Age  for  $2.00. 

Carefully  selected  standard  texts  on  these  subjects  will  be  recom- 
mended to  students  who  desire  them,  for  more  intensive  study  or 
references. 

A  membership  period  in  the  Marconi  Institute  Extension  Training 
Course  extends  over  one  year.  During  that  time  each  member  should 
keep  in  close  touch  with  the  Institute  and  secure  helpful  guidance  and 
co-operation. 

COST 

The  Institute  Training  Service  for  Schools  and  individuals  com- 
prises the  following  publications : 

Wireless  Age,  yearly  subscription $2.00 

Practical   Wireless  Telegraphy    1.50 

How  to  Pass  U.  S.  Government  Wireless  License  Ex- 
amination  50 

Radio  Telephony 2.00 

Military  Signal  Corps  Manual 1.50 

Victor  Records  for  Code  Practice (12  lessons)      5.00 

*Key,  Buzzer,  Head  Telephones  and  Condenser  for  Code 
Practice 9.00 

These  items  may  be  ordered  separately,  as  required,  or  in  combina- 
tion at  a  discount  of  10  per  cent,  on  the  magazine  and  text  books,  but 
not  on  the  Records  and  Apparatus. 


*Price  subject  to  change. 


44  MARCONI   INSTITUTE 

TEXT  BOOKS  AND  SPECIAL  WIRELESS   LITERATURE 

After  careful  examination  of  available  wireless  literature  the  fol- 
lowing texts  for  class  and  extension  course  study  have  been  selected. 

In  addition,  books  for  collateral  reading,  selected  upon  recommen- 
dation of  the  prominent  educators  throughout  the  United  States,  are 
listed. 

For  radio  schools  offering  a  general  technical  and  code  course,  the 
following  books,  which  are  the  official  text  books  of  the  Marconi  Insti- 
tute should  be  used : 

PRACTICAL  WIRELESS  TELEGRAPHY 
By  Elmer  E.   Bucher,  Director  of   Instruction,   Marconi   Institute 

This  book  is  the  last  word  in  wireless  text  books.  It  furnishes 
information  of  utmost  value  in  regard  to  the  very  latest  styles  of  wireless  sets 
now  in  use,  and  which  has  not  appeared  in  print  before. 

PRACTICAL  WIRELESS  TELEGRAPHY  is  the  first  wireless  text 
book  to  treat  each  topic  separately  and  completely,  furnishing  a  progressive 
study  from  first  principles  to  expert  practice.  Starting  with  elementary  data, 
it  progresses,  chapter  by  chapter,  over  the  entire  field  of  wireless — funda- 
mentals, construction  and  practical  operation. 

Three  chapters  are  devoted  entirely  to  how  to  tune  a  transmitter  and  receiving- 
basic  electrical  principles.  The  motor-  set,  how  to  measure  inductance  and 
generator,  the  dynamotor  and  rotary  capacity  of  radio  telegraphic  circuits, 
converter  are  treated  in  detail.  The  how  to  determine  the  strength  of  in- 
nickel-iron  and  lead  plate  storage  bat-  coming  signals  and  the  method  of  plot- 
teries,  now  supplied  for  emergency  pur-  ting  resonance  curves.  A  complete  ex- 
poses with  all  commercial  radio  equip-  planation  of  ships'  tuning  records,  Gov- 
ments  are  the  subject  of  an  entire  chap-  ernment  tuning  cards  and  everything 
ter,  a  description  of  the  apparatus  pertaining  to  the  adjustment  of  a  wire- 
associated  with  the  charging-  of  bat-  less  telegraph  transmitter  and  receiver 
teries  and  complete  instructions  for  is  published, 
their  care  being  furnished.  The  emergency  transmitters  and  aux- 

The  radio  transmitter  is  treated  both  iliary  power  apparatus  of  modern  ship 
in  theory  and  in  practice.  The  book  wireless  sets  are  thoroughly  described 
contains  complete  diagrams,  photo-  and  illustrated.  Descriptions  in  detail 
graphs  and  descriptions  of  modern  com-  and  principle  of  the  Marconi  direction 
mercial  marine  transmitters  and  in-  finder  are  given  and  modern  undamped 
structions  for  the  adjustment  and  op-  wave  transmitters  and  receivers  are 
eration  of  the  apparatus.  Receiving  comprehensively  told  of. 
apparatus  is  treated  in  like  manner,  The  student,  for  the  first  time,  is 
descriptions  and  working  instructions  given  a  complete  description  of  Mar- 
being  given  for  all  types  of  up-to-date  coni  trans-oceanic  stations,  including 
receiving  sets,  including  the  two  and  their  fundamental  working  principles, 
three-electrode  valves.  the  details  of  the  apparatus  and  the 

A  full  chapter  is  devoted  to  practical  general  plan  of  the  great  globe-girdling 

radio  measurements,   showing   in   detail  scheme  of  the  Marconi   system. 

The  340  illustrations  alone,  specially  drawn,  form  a  complete  diagrammatic 
study  and  impress  upon  the  reader's  mind  a  pictorial  outline  of  the  entire  sub- 
ject. Many  of  these  illustrations  reveal  details  of  construction  of  the  newest 
types  of  sets  and  apparatus  never  before  published. 

PRACTICAL  WIRELESS  TELEGRAPHY  is  a  practical  man's  book  from 
cover  to  cover  and  up  to  the  minute. 

Size  330  pp.,  6x9  inches.    Price  $1.50  net. 


MARCONI    INSTITUTE  45 

TRAFFIC  RULES  AND  REGULATIONS 

We  issued  this  compact  volume  for  the  MARCONI  WIRELESS  TELEGRAPH  COM- 
PANY OF  AMERICA. 

At  the  request  of  several  radio  schools,  who  believe  it  will  be  of  the  utmost 
value  to  their  students  now  preparing  for  professional  wireless  service,  we  offer 
a  limited  number  of  copies  for  sale  to  persons  who  are  deeply  interested  and 
who  wish  to  master  the  details  of  practical  wireless  service. 

It  contains  complete  instructions  covering  every  feature  connected  with 
the  routing  and  handling  of  wireless  traffic;  an  interpretation  of  the  Interna- 
tional Wireless  Telegraph  Convention  rules  as  applied  to  commercial  practice; 
conduct  of  wireless  operators  at  sea  and  the  method  of  accounting  for  traffic 
with  affiliated  companies. 

CONTENTS  —  General    Instructions—       Canada—  Abstracting    of    Messages    and 


tion  —  International  Telegraph  Conven-  Map  of  Principal  Trans-Oceanic  Wire- 
tA1?,n'^;TTl,S-  Radio  Law—  Rates  Through  less  Stations  and  Coast  Stations  of  the 
All  Stations  of  the  United  States  and  World. 

Cloth  12m  o.    Price  $1.00  net. 


HOW      TO      PASS      U.      S.      GOVERNMENT      WIRELESS      LICENSE 

EXAMINATIONS 

By  Elmer  E.  Bucher 

Prepared  as  a  guide  for  radio  operators  training  for  the  Government  License 
Examination.  Third  Edition  Largely  Revised  and  Extended.  One  hundred  and 
forty-two  Questions  and  Answers. 

CONTENTS— Explanation    of   Electri-  V.       Receiving      Apparatus  —  Part      VI. 

cal    Symbols — Definitions    of    Electrical  Radio  Laws  and  Regulations — Part  VII. 

Terms — Part    I.    Transmitting    Appara-  General    Information    Concerning   Oper- 

tus — Part    II.    Motor    Generators — Part  ator's   License  Examinations — Practical 

III.  Storage  Batteries  and  the  Auxiliary  Equations      for      Radio      Telegraphy — 

Set — Part  IV.  Antenna  or  Aerials — Part  Equations    for    Ordinary    Power    Work. 

Price  SQC  net. 


MILITARY  SIGNAL  CORPS  MANUAL 
By  Major  J.  Andrew  White,  Chief  Signal  Officer  of  the  Junior  American  Guard 

This  manual,  the  first  of  its  kind  and  the  only  complete  work  on  the 
broad  subject  of  army  signaling,  is  indispensable  to  those  responding  to  the 
call  to  the  colors.  Primarily  prepared  for  Signal  Corps  men,  it  is  a  necessity 
for  the  proper  understanding  of  their  apparatus  and  the  tactical  employment 
of  troops  and  equipment. 

Officers  of  infantry  and  artillery  will  find  the  volume  of  great  utility,  a 
proper  conception  of  the  enormously  enlarged  Service  of  Information  being 
indispensable  to  all  commissioned  men. 

Its  contents  include  administration  and  government  of  military  units — 
tactics  of  the  division  on  the  march,  at  rest  and  in  engagement — function  and 
operations  of  the  Signal  Corps  and  its  relation  to  the  line  of  the  army — drill 
instruction,  mounted  and  dismounted,  for  telegraph  companies,  radio  and 
outpost  companies,  and  battalions  of  Signal  Corps — signaling  by  telegraph, 
heliograph,  night  lantern  and  flags,  radio  and  service  buzzer — camp  and  field 
telephones  and  their  uses — radio  apparatus  of  the  Signal  Corps — scouting, 
patrolling  and  tactical  employment  of  field  lines. 

Prepared  with  the  full  co-operation  and  approval  of  the  Chief  Signal 
Officer,  U.  S.  Army. 

550  pages.    260  illustrations.    Price  $1.50. 


46  MARCONI    INSTITUTE 

RADIO   TELEPHONY 
By  Alfred  N.  Goldsmith,  Ph.  D. 

Fellow  of  the  Institute  of  Radio  Engineers 
Member  of  the  American  Institute  of  Electrical  Engineers 

Director   of   the   Radio    Telegraphic  and    Telephonic   Laboratory 
of  the  College  of  the  City  of  New  York 

This  complete  text  on  radio  telephony  is  intended  for  radio  engineers, 
radio  electricians  in  the  Navy,  men  in  the  Signal  Corps  and  especially 
men  in  the  Aviation  Service  who  handle  radio  equipment.  Amateurs  and 
others  who  desire  to  be  clearly  informed  concerning  this  newest  and 
most  interesting  branch  of  electric  communication  will  want  this  book. 

It  is  written  in  clear  style,  and  presupposes  very  little  knowledge  of  radio. 
The  text  deals  largely  with  the  practical  aspects  of  radio  telephony  and 
its  future.  It  is  copiously  illustrated  with  wiring  diagrams  and  previ- 
ously unpublished  photographs  of  "wireless  telephone"  apparatus. 

IT  IS  THE  ONLY  BOOK  TREATING  THE  SUBJECT  OF 
RADIO  TELEPHONY  IN  ALL  ITS  ASPECTS. 

Among  the  unusual  features  of  the  book  are  a  description  of  how  radio 
telephony  was  carried  on  over  a  distance  of  more  than  5,000  miles ;  an 
illustrated  description  of  an  airplane  radio  telephone  set ;  an  illustrated 
description  of  a  large  ship  radiophone  set;  numerous  illustrated  sections 
on  smaller  ship  "wireless  telephone"  transmitters ;  land  station  radio  tele- 
phone sets  of  all  sizes. 

Another  noteworthy  feature  is  a  description  of  the  method  of  transmit- 
ting a  radio  telephone  message  to  a  ship  at  sea,  or  across  continent  or 
ocean,  including  the  number  of  persons  involved.  This  material  is  in 
dialogue  form  and  so  worded  as  to  require  no  previous  knowledge  of 
the  subject. 

Among  the  topics  treated  are :  the  construction  and  operation  of  the  Arm- 
strong oscillating  audion  circuits ;  the  construction  and  use  of  bulb  ampli- 
fiers; the  construction  of  the  great  alternators  of  the  Alexanderson  and 
Goldschmidt  systems  and  how  they  are  controlled,  especially  for  radio 
telephony. 

The  book  is  very  complete,  practically  every  aspect  of  radio  telephony 
being  covered  in  detail.  There  are  over  400  separate  topics  listed  in  a 
carefully  prepared  index. 

8vo.    256  pages.    226  illustrations.    Full  cloth,  stamped  in  gold.    Price  $2.00  net. 


MARCONI    INSTITUTE 


47 


The  following  leaders  of  thought  in  the  Wireless  and  Electrical 
Engineering  fields  in  the  United  States  co-operated  in  compiling  a 
list  of  reference  works  for  use  as  additional  study  texts  and  for  collat- 
eral reading  in  connection  with  study  courses  in  Wireless  telegraphy 
and  telephony. 


ARKANSAS 

BROWN,  H.  A.  Instructor  in  Electrical 
Engineering,  UNIVERSITY  OF  ARKANSAS. 

CALIFORNIA 

RYAN,  HARRIS  J.  Professor  of  Electrical 
Engineering,  LELAND  STANFORD  JR.  UNIVER- 
SITY. 

HUND,  AUGUST.  Assistant  Professor  of 
Electrical  Engineering,  UNIVERSITY  OF 
SOUTHERN  CALIFORNIA. 

COLORADO 

PERSON,  FREDERICK  G.  Professor  of 
Physics  and  Electrical  Engineering,  THE 
STATE  AGRICULTURAL  COLLEGE  OF  COLORADO. 

DISTRICT  OF   COLUMBIA 

MORTIMER,  CHARLES  W.  Professor  of 
Electrical  Engineering,  GEORGE  WASHING- 
TON UNIVERSITY. 

ILLINOIS 

BIRREN,  EDWARD  G.  Engineering  Li- 
brarian, DE  PAUL  UNIVERSITY. 

IOWA 

WRIGHT,  C.  A.  Associate  Professor  of 
Electrical  Engineering,  IOWA  STATE  COL- 
LEGE. 

SHANE,  ADOLPH.  Dean  of  College  of 
Engineering,  HIGHLAND  PARK  COLLEGE. 

KANSAS 

REID,  CLARENCE  E.  Professor  of  Elec- 
trical Engineering,  KANSAS  STATE  AGRICUL- 
TURAL COLLEGE. 

KENTUCKY 

FREEMAN,  PROFESSOR  W.  E.  UNI- 
VERSITY OF  KENTUCKY. 

LOUISIANA 

ANDERSON,  DOUGLAS.  Professor  of 
Electrical  Engineering,  TULANE  UNIVERSITY 
OF  LOUISIANA. 

MAINE 

BARROWS,  W.  E.  Professor  of  Elec- 
trical Engineering,  UNIVERSITY  of  MAINE. 

MARYLAND 

WHITEHEAD,  PROFESSOR  JOHN  B. 
JOHNS  HOPKINS  UNIVERSITY. 

MICHIGAN 

SHEPPARD,  H.  S.  Assistant  Professor 
of  Electrical  Engineering,  UNIVERSITY  OF 
MICHIGAN. 

MISSISSIPPI 

KENNON,  W.  L.  Professor  of  Physics, 
UNIVERSITY  OF  MISSISSIPPI. 


MOODY,    H.     W.      Professor    of    Physics, 
MISSISSIPPI    AGRICULTURAL    AND    MECHANI- 
CAL COLLEGE. 
MISSOURI 

LANGSDORF,  A.  S.  Professor  of  Elec- 
trical Engineering,  WASHINGTON  UNIVER- 
SITY. 

MONTANA 

THALER,  J.  A.,  Professor  of  Electrical 
Engineering,  MONTANA  STATE  COLLEGE  OF 
AGRICULTURE  AND  MECHANIC  ARTS. 

NEW  HAMPSHIRE 

AUSTIN,  F.  E.  Professor  of  Electrical 
Engineering,  THAYER  SCHOOL  OF  CIVIL 
ENGINEERING. 

NEW   JERSEY 

MACLAREN,  MALCOLM.    Professor    of 

Electrical  Engineering,  PRINCETON  UNIVER- 
SITY. 

NEW   YORK 

COOK,  ARTHUR  L.  Head  of  the  Depart- 
ment of  Applied  Electricity,  PRATT  INSTI- 
TUTE. 

OHIO 

WILSON,  A.  M.  Professor  of  Electrical 
Engineering,  UNIVERSITY  OF  CINCINNATI. 

OREGON 

DEARBORN,  R.  H.  Head  of  Department 
of  Electrical  Engineering,  OREGON  AGRICUL- 
TURAL COLLEGE. 

PENNSYLVANIA 

WURTS,  ALEXANDER  J.  Professor  of 
Electrical  Engineering,  CARNEGIE  INSTITUTE 
OF  TECHNOLOGY. 

HARRIS,  L.  H.  Professor  of  Electrical 
Engineering,  UNIVERSITY  OF  PITTSBURGH. 
ROOD,  JAMES  T.  Professor  of  Electrical 
Engineering,  LAFAYETTE  COLLEGE. 

RHODE  ISLAND 

WATSON.  ARTHUR  E.  Professor  of 
Electrical  Engineering,  BROWN  UNIVERSITY. 

SOUTH  DAKOTA 

BRACKETT.     BYRON    B.       Professor    of 

Electrical      Engineering,      SOUTH      DAKOTA 

STATE  COLLEGE. 
WASHINGTON 

CARPENTER,  PROFESSOR  H.  V.  STATE 

COLLEGE  OF  WASHINGTON. 

WISCONSIN 

BENNETT,  EDWARD.  College  of  Me- 
chanics and  Engineering,  THE  UNIVERSITY 
OF  WISCONSIN. 


The  books  recommended  are  listed  on  pages  48  and  49. 

This  literature,  used  in  connection  with  the  extension  study  courses 
in  THE  WIRELESS  AGE  will  materially  aid  the  student  to  prepare  for 
efficient  service  in  the  Army  or  Navy,  or  in  the  merchant  marine. 


48  MARCONI    INSTITUTE 

BOOKS  FOR   COLLATERAL   READING 

The  Principles  of  Electric  Wave  Telegraphy.  By  J.  A.  Fleming,  M.  A., 
D.  Sc.,  F.  R.  S.,  Professor  of  Electrical  Engineering  in  the  University  of  Lon- 
don, Member  of  the  Royal  Institution  of  Great  Britain. 

A  complete  reference  book,  historical,  theoretical,  practical.  A  resume 
of  the  art  of  electric  wave  telegraphy.  The  book  has  recently  been 
revised  and  brought  up  to  date. 

Cloth  8vo.     912  pages.     Illustrated.     Price   $10.00   net. 

Wireless  Telegraphy.  By  Dr.  J.  Zenneck,  Professor  of  Physics  at  the  Techni- 
cal High  School  of  Munich. 

Devoted    to    theoretical    and    practical    instruction    in    the    art    from    the 
German  viewpoint.    Covers  practice  up  to  the  year  1912. 
Cloth.    443  pages.     461  Illustrations.     Price  $4.00. 

Principles  of  Wireless  Telegraphy.  By  Professor  George  W.  Pierce,  A.M.,  Ph.D., 

Assistant  Professor  of  Physics  in  Harvard  University. 

A  valuable  textbook  for  all  students  of  radio.  Particularly  devoted 
to  a  discussion  of  contact  rectifiers  in  wireless  telegraphy  and  to  the 
relative  merits  of  early  wireless  inventors'  claims. 

Cloth.    350  pages.    235  illustrations.    Price  $3.00. 

Wireless  Telegraphy  and  Telephony.  By  A.  E.  Kennelly,  M.  A.,  D.  Sc.,  Pro- 
fessor of  Electrical  Engineering  in  Harvard  University. 

Specially  recommended  to  those  who  want  a  simple  explanation  of  the 
theory     of     electric     wave     propagation.       Treats     the     fundamentals     of 
radio  telegraphy  and  telephony  in  a  simple,  interesting  manner. 
Cloth.     279  pages.     Illustrated.     Price  $1.25. 

Textbook  on  Wireless  Telegraphy.     By  Rupert  A.  Stanley,  B.  A.,  M.  I.  E.  E., 

Professor  of  Physics  and  Electrical  Engineering,  Municipal   Technical  Insti- 
tute, Belfast. 

An     elementary     text     book     covering,     principally,     European     practice. 

Gives  descriptions  of  the  Marconi  and  Telefunken   systems. 
Cloth.     8vo.     340  pages.     Illustrated.     Price  $2.50. 

Handbook  of  Technical  Instruction  for  Wireless  Telegraphists.  By  J.  C. 
Hawkhead  and  H.  M.  Dowsett. 

Covers  European  practice  in  the  English  Marconi  Company.  A  very 
complete  work  for  sea-going  telegraphists. 

Cloth.     309  pages.     Illustrated.     Price  $1.50  net. 

How  to  Conduct  a  Radio  Club.    By  Elmer  E.  Bucher,  M.  I.  R.  E. 

A     complete     experimenter's    manual.       Invaluable     information     for     the 
experimenter  or  the  professional  radio  telegraphist. 
8vo.     134  illustrations.     Price  5Of.   net. 

Radio  Telegraphy  and  Radio  Telephony.  By  J.  A.  Fleming,  M.  A.,D.  Sc.,  F.  R.  S. 

Devoted    to    the    fundamental    principles    of    wireless    telegraphy    and    to 
practice    in   Europe.      Valuable    for    elementary    students    of    radio    teleg 
raphy.    The  book  has  recently  been  revised  and  enlarged. 
Cloth.     8vo.     360  pages.     Price  $2.50. 

The  Proceedings  of  the  Institute  of  Radio  Engineers.  Edited  by  Alfred  N. 
Goldsmith,  Ph.D.,  of  the  Institute  of  Radio  Engineers  and  College  of  the  City 
.of  New  York. 

Students  desiring  to  keep  in  touch  with  the  very  latest  developments 
of  wireless  telegraphy  should  not  fail  to  subscribe  to  these  proceedings. 
Recent  inventions  in  radio  are  accurately  and  fully  described  by  the 
engineers  who  discovered  them. 

Buckram   binding.     Price   $7.00   net. 

Elementary  Principles  of  Wireless  Telegraphy.     By  R.  D.  Bangay. 

Explains  in  the  simplest  manner  possible  the  theory  and  practice  of 
wireless  telegraphy.  It  is  especially  useful  to  Boy  Scout  organizations 
or  elementary  classes  in  radio. 

Cloth.     I2mo.     241  pages.     Price  75c  net. 


MARCONI    INSTITUTE  49 

BOOKS   ON   ELECTRICITY  AND    MAGNETISM   FOR   COLLATERAL 

READING 

Practical  Electricity.     By  C.  Walton  Swoope.,     Member  American   Institute   of 
Electrical  Engineers. 

One  of  the  most  complete  elementary  books  on  general  electrical  prac- 
tice ever  published.  Invaluable  to  beginners  who  desire  basic  knowl- 
edge of  electricity  and  magnetism. 

Cloth.     517  pages.     404  illustrations.     Price  $2.00  net. 

Elementary  Lessons  in  Electricity  and  Magnetism.    By  Silvanus  P.  Thompson. 
Has  been  on  the  market  for  a  number  .of  years.     Recently  been  revised 
and  brought  up  to  date.     The  standard  text  book  in  many  colleges. 
Cloth.     706  pages.     Price  $1.50  net. 

Telegraph  Engineering.     By  Erich  Hausmann,  Ph.  D.,   Assistant   Professor   of 
Physics  and  Electrical  Engineering,  Polytechnic  Institute  of  Brooklyn. 

A  class  room  manual  for  practical  telegraph  engineering  students. 
Up-to-date  and  especially  recommended  to  those  who  desire  knowledge 
of  modern  practice. 

Cloth.     8>vo.     416  pages.     Price  $3.00  net. 

A  Short  Course  in  the  Testing  of  Electrical  Machinery.     By  J.  H.  Morecroft 
and  F.  W.  Hehre. 

Invaluable   to   the   laboratory   man.     An    analysis   of   the    subject   written 
in  non-mathematical  form  and  particularly  applicable  to  the  beginner. 
Cloth.     8vo.     88  illustrations.     Price  $1.50. 

Applied  Electricity  for  Practical  Men.     By  Arthur  J.  Rowland,  Professor  oj 
Electrical  Engineering  at  the  Drexel  Institute,  Philadelphia. 

A  very  clear  treatment  of  the  application  of  electrical  engineering 
written  from  the  standpoint  of  the  worker  who  intends  to  operate 
commercial  electrical  machinery. 

Cloth.     375  pages.     323  illustrations.     Price  $2.00  net. 

Advanced  Theory  of  Electricity  and  Magnetism.    By  William  S.  Franklin  and 
Barry  MacNutt. 

A  complete  text  book  for  colleges  and  technical  schools.  One  of  the 
most  advanced  works  in  its  field  but  presented  in  a  way  easily  understand- 
able to  the  beginner. 

Cloth.    87*0.    300  pages.    Illustrated.    Price  $2.00  net. 

High  Frequency  Apparatus.     By  Thomas  Stanley  Curtis. 

Shows  the  non-technical  man  how  to  build  high  frequency  apparatus 
for  special  experiments;  also  describes  some  of  the  best  methods  of 
construction  used  in  the  largest  manufacturing  establishments.  Sim- 
plified for  the  amateur's  needs. 

Cloth.     $2.00 

Direction  for  Designing,  Making  and  Operating  High  Pressure  Transformers. 
By  F.  E.  Austin. 

Describes    and    explains    the    design    of    high    voltage    transformers 
detail.     Shows  their  necessity  in  commercial  ivork.    Profusely  illustrated. 
Cloth.    6$c. 

BOOKS  ON  WIRELESS  TELEGRAPHY  FOR  AMATEURS 

Wireless  Telegraph  Construction  for  Amateurs.    By  Alfred  P.  Morgan. 

Gives  complete  instruction  for  building  amateur  transmitting  and  receiving 
apparatus.  Also  explains,  briefly,  the  theory  of  each  part  and  gives  direc- 
tions for  operating. 

Cloth.     225  pages.     167  illustrations.     Price  $1.50. 

Experimental  Wireless  Stations.     By  Philip  E.  Edleman 

A  book  devoted  to  the  theory,  design,  construction  and  operation  of  experi- 
mental wireless  equipment.   "Contains  much  up-to  date  information. 
Cloth.     272  pages.     Illustrated.     Price  $1.50. 


in 


50 


MARCONI    INSTITUTE 


THE    MARCONI    WIRELESS    RECORDS    FOR    CLASS    AND    HOME 

CODE  INSTRUCTION 

By  Harry  Chadwick,  Traffic  and  Code  Instructor  of  the  Marconi  Institute 

The  practical  solution  of  the  greatest  problem  encountered  in  self- 
training  in  the  international  telegraph  code.  A  complete  set  of  disc- 
Victrola  records  specially  prepared  for  students  of  radiotelegraphy. 

A  description  of  each  of  the  lesson  records  follows : 

Lesson  1. —  Each  letter  and  figure  of  the  International  Morse  code  announced 
and  then  signaled  three  times.  This  record  was  prepared  for 
the  novice. 

Lesson  2. —  Gives  the  conventional  signals  allied  with  the  International 
Morse  code. 

Lesson  3. —  A  trial  record  for  the  student  who  can  recognize  the  letters  of 
the  code  by  sound.  Contains  easy  sentences  which  have  been 
found  particularly  useful  for  training  the  beginner.  The  sen- 
tences are  reproduced  at  ten  words  per  minute. 

Lesson  4. —  Contains  easy  sentences  at  fifteen  words  per  minute.  Numerals 
are  introduced  in  this  record  to  aid  the  student's  progress. 

Lesson  5. —  A  partial  reproduction  of  a  press  message  dispatched  from  the 
Marconi  high  power  station  at  South  Wellsfleet,  Massachusetts. 

Lesson  6. —  Simple  radio  messages  with  "static"  interference.  Trains  the 
student  to  read  through  interfering  discharges  of  atmospheric 
electricity. 

Lesson  7. —  This  record  introduces  a  specimen  press  message  with  atmos- 
pheric interference.  The  signals  will  reproduce  at  eighteen 
words  per  minute. 


Lesson    8. 
Lesson     9. 


Specimen    commercial    radio   messages    introducing   the    erasure 
signal. 


Contains  two  press  messages  sent  out  simultaneously  by  two 
spark  transmitters  of  different  pitch.  Teaches  the  student  to  read 
signals  through  the  interference  of  another  station. 

Lesson  10. —     Devoted  entirely  to  numerals. 

Lesson  11. —     Introduces    ten-letter    words    to    prepare    the    student    for    more 
difficult  copying. 

Lesson  12. —     Devoted   to  artificial   code  words,   giving  invaluable   instruction 
to  the  advanced  student. 


Indispensable  to  the  Learner.     A  Valuable  Assistant  for  Instruc- 
tion in  Government  Radio  Schools. 

Complete  set  of  12  lessons,  on  six  double-faced  records,  with  in- 
struction manual,  price  $5.00. 

MARCONI  INSTITUTE 


25  Elm  Street, 


New  York  City 


CREATION,  GROWTH  AND  DEVELOPMENT  OF  THE 
MARCONI  WORLD-WIDE  SYSTEM 

"OADIO-SIGNALING,  or  the  art  of  signaling  by  radiant  waves,  was 
*-*•  originated,  created,  and  developed  by  Marconi,  and  to  him  and  the 
great  companies  bearing  his  name,  formed  to  commercialize  his  genius, 
we  owe  the  development  of  the  art  from  small  beginnings  to  world-wide 
achievement. 

The  transmission  of  intelligence  through  space,  without  any  formal 
conducting  medium,  was  practiced  in  ancient  Egypt,  and  through  past 
centuries  by  auditory  and  visual  methods,  including  the  beacon  fire,  the 
semaphore,  the  heliograph,  and  the  cannonade.  These  methods  had 
such  obvious  limitations,  however,  that  they  gave  way  to  electrical  trans- 
mission, upon  the  discovery  of  the  electric  telegraph. 

The  art  of  transmitting  intelligence  by  electricity  is  in  fact  a  group 
of  arts,  included  broadly,  under  methods  of  wire  transmission  and 
methods  of  wireless  transmission.  Wireless  telegraphy  and  radioteleg- 
raphy  have  been  considered,  in  the  popular  mind,  as  synonymous  terms, 
but  radiotelegraphy,  or  radio-signaling,  is  an  art  coming  under  the 
broad  classification  of  wireless  transmission.  It  involves  communica- 
tion by  electric  waves  through  the  ether,  and  has  nothing  to  do  with 
the  older  methods  of  electric  conduction  through  earth  or  water,  or 
electromagnetic  or  electrostatic  induction,  in  which  the  waves  actually 
reach  from  one  station  to  another  and  are  not  detached  from  the  send- 
ing station  and  transmitted  through  space,  as  in  radio-signaling. 

The  conduction  and  induction  methods  had  been  tried  without  ma- 
terial success,  due  to  inherent  limitations,  when  Marconi  created  the 
new  art  of  radiotelegraphy,  one  of  the  greatest  inventions  of  all  time, 
and  afterward  destined  to  become  one  of  the  greatest  factors  of  modern 
civilization. 

The  first  man  to  transmit  intelligence  electrically  was  Morse.  He 
did  it  by  utilizing  certain  well-known  electrical  appliances — the  battery, 
the  direct  current,  the  magnet,  connecting  wires,  and  the  key  at  the 
transmitter.  That  was  the  first  one  of  this  group  of  arts  for  transmit- 
ting intelligence  electrically. 

The  second  was  the  Bell  invention  of  the  telephone.  Bell  also  util- 
ized things  that  were  known  in  electrical  science,  as  the  undulatory 
current,  the  magnet  and  diaphragms,  and  the  connecting  wires. 

Morse,  the  father  of  electric  telegraphy,  originated  an  art  which 

51 


52 


MARCONI    INSTITUTE 


was  of  enormous  value.  Bell,  who  originated  the  art  of  telephony,  also 
created  something  of  great  value.  The  art  of  conduction  through  the 
earth  or  water,  and  signaling  by  means  of  electromagnetic  or  electro- 
static induction,  however,  has  not  been  of  any  considerable  public  bene- 
fit. But  the  art  that  Marconi  created,  the  art  of  radio-signaling,  was 


Shows  a  type  of  receiving  apparatus  that  has  been  especially  useful 
in  naval  and  war  operations.  These  four  pieces  of  apparatus  constitute 
a  complete  Marconi  Bellini-Tosi  Direction  Finder  by  which  the  receiving- 
operator  may  locate  the  position  of  a  wireless  sending  station.  The 
apparatus  shown  has  a  range  of  wave  lengths  up  to  600  meters  and  will 
locate  the  direction  of  the  propagation  of  electrical  waves  with  a  notable 
degree  of  accuracy.  Special  types  of  this  apparatus  have  been  developed 
for  use  on  wave  lengths  up  to  10,000  meters,  and  with  it  signals  have 
been  received  across  the  Atlantic  ocean.  The  complete  direction  finder 
equipment  consists  of  a  radio  ganiometer,  a  tuned  buzzer  detector,  a 
divider,  and  complete  receiving  set  with  tuning  appliances. 

of  enormous  value  to  mankind,  and  stands  as  an  art  by  itself,  in  the 
group  relating  to  the  transmission  of  intelligence  by  electricity. 

Marconi's  epoch-making  achievement  will  be  better  understood  by 
considering  briefly  the  history  of  this  group  of  arts  to  which  his  inven- 
tion relates. 

PRIOR  CLASSES  or  TELEGRAPHY 

Extending  over  a  period  of  fifty  or  sixty  years  prior  to  1896,  many 
of  the  most  distinguished  scientists  and  inventors  of  the  world  had  en- 
deavored to  devise  a  system  of  communicating  intelligence  telegraph- 
ically from  one  point  to  another  without  the  use  of  conducting  wires. 


MARCONI    INSTITUTE  53 

Such  renowned  scientists  as  Faraday,  Morse,  Lord  Kelvin,  Henry, 
and  Sir  William  Preece,  had  endeavored  to  solve  this  problem  by  means 
of  arrangements  of  apparatus  adapted  to  utilize  electric  phenomena; 
these  may  be  divided  into  three  classes  or  methods. 

First  in  order  of  time  was  the  conduction  system,  the  essential 
feature  of  which  is  that  some  other  form  of  material  conductor  is 
substituted  for  wires.  These  substitutes  were  in  all  cases  either  the 
earth  or  bodies  of  water,  since  they  are  the  only  natural  conductors 
that  are  sufficiently  common  and  extensive  for  use.  This  method  was 
preferably  employed  by  means  of  wires  which  were  stretched  along 
both  banks  of  a  river  and  grounded  at  both  ends,  the  length  of  wire  on 
both  sides  of  the  river  being  greater  than  the  distance  by  which  the  wires 
were  separated  from  each  other.  If,  then,  a  current  was  set  up  in  one 
wire,  a  certain  amount  of  this  current  would  leak  across  the  intervening 
space  and  produce  current  in  the  wire  on  the  other  side  of  the  river. 
By  means  of  a  circuit  maker  and  breaker  signals  were  thus  transmitted 
from  one  bank  to  the  other. 

It  appears  that  Professor  Morse  discovered  this  method  of  com- 
munication as  early  as  1842,  while  giving  a  public  demonstration  in 
New  York  of  the  practicability  of  his  wire  telegraph.  A  passing  vessel 
parted  the  wires,  which  he  had  stretched  from  Governor's  Island  to 
Castle  Garden,  and  in  his  discomfiture  he  immediately  devised  a  plan 
for  avoiding  such  accidents  in  the  future,  by  so  arranging  wires  along 
the  banks  of  the  river  as  to  cause  the  water  itself  to  act  as  a  conductor 
for  the  electric  current. 

Sir  William  Preece,  the  engineer  of  the  British  Postal  Service, 
subsequently  worked  out  more  extensive  methods  of  operation  upon 
this  principle,  but  the  distance  covered  did  not  exceed  two  or  three 
miles,  and  the  large  amount  of  wire  required  was  a  curious  feature  of 
this  system  of  so-called  "wireless  telegraphy." 

The  second  method  originally  employed  by  the  scientists  and  inven- 
tors, known  as  the  "inductive  system,"  furnished  a  wider  field  of 
experiment.  Of  this  there  are  two  types;  electromagnetic  induction, 
and  electrostatic  induction.  The  electromagnetic  induction  method 
operated  by  the  production  of  a  magnetic  field  in  one  complete  circuit, 
which  induced  a  current  in  another  complete  circuit,  by  virtue  of  mag- 
netic lines  stretched  or  extending  from  the  transmitting  circuit  to  the 
receiving  circuit.  This  method  was  also  used  by  Sir  William  Preece 
in  England,  who  was  able  to  telegraph  a  short  distance.  This  method 


MARCONI    INSTITUTE 


\ 

CLOSED  CORE 
TRANSFORMER 


There  has  been  an  insistent  demand  in  shipping-  circles  for  low 
power  transmitters  for  use  on  cargo  vessels.  For  these  vessels  trans- 
mitting- apparatus  was  required  which  could  be  placed  in  the  hands  of 
operators  who  were  not  highly  skilled  in  the  technical  operation  of  radio 
sets.  The  American  Marconi  Company  developed  a  %  K.  W.  special 
cargo  type  of  transmitting  apparatus  which  met  with  universal  favor. 
The  transmitter  shown  in  the  photograph  consists  of  a  motorgenerator, 
high  voltage  transformer,  high  voltage  condenser,  oscillation  trans- 
former and  short  wave  condenser.  The  motorgenerator  is  fitted  with  a 
hand-operated  starter.  This  apparatus  will  permit  communication  over 
several  hundred  miles  and  is  highly  suitable  for  the  special  grade 
of  service  required  on  cargo  vessels. 


MARCONI   INSTITUTE  55 

of  wireless  telegraphy  was  also  applied  to  railroad  telegraphy.  Im- 
pulses produced  in  a  wire  extending  along  the  track  were  communicated 
to  a  moving  train  carrying  a  circuit  which  was  connected  through  the 
wheels  to  the  rails  at  opposite  ends  of  the  car. 

The  third  method,  known  as  electrostatic  induction,  differs  from  the 
electromagnetic  method  in  that  it  does  not  make  use  of  a  magnetic  field 
but  depends  upon  high  voltage  or  pressure  for  the  purpose  of  "charging 
the  earth,"  so  to  speak.  Professor  Dolbear,  of  Tuft's  College,  in  1886, 
and  Thomas  A.  Edison,  in  1891,  devised  systems  for  signaling  by  the 
electrostatic  method.  These  systems  of  wireless  telegraphy  by  conduc- 
tion and  induction  are  of  historical  rather  than  practical  value.  Their 
utility  was  very  limited  and  the  cost  of  installation  was  even  greatly  in 
excess  of  the  cost  of  wire  telegraphy.  They  were  obviously  imprac- 
ticable for  commercial  use  because  the  messages  or  signals  could  only 
be  transmitted  a  very  short  distance,  owing  to  the  fact  that  they  all 
depended  upon  the  electrical  energy  at  the  transmitting  circuit  stretch- 
ing or  extending  to  the  receiving  circuit.  There  was  no  detachment  or 
radiation  of  the  electrical  energy  from  the  transmitting  source  as  in 
radiotelegraphy. 

These,  then,  were  the  prior  proposed  methods  of  wireless  telegraphy. 
The  art  of  radiotelegraphy  created  by  Marconi  operated  by  virtue  of 
new  and  different  electric  phenomena. 

THE  PERIOD  OF  SPECULATION — HERTZIAN  WAVES 

In  1863  the  eminent  physicist  J.  Clerk  Maxwell,  theoretically  specu- 
lated that  the  medium  known  as  "ether"  should  be  able  to  transmit 
through  it  disturbances,  with  a  velocity  equal  to  that  of  light. 

In  1887  these  theoretical  speculations  of  Maxwell  were  confirmed  by 
the  experiments  of  Hertz,  who  showed  that  electric  oscillations  which 
for  many  years  had  been  known  to  exist  in  metal  rods,  were  propagated 
out  into  space  from  these  rods  in  the  form  of  wave  motion,  when  a  very 
sudden  electrical  discharge  took  place  between  the  rods.  These  Hertz- 
ian waves  are  propagated  in  the  universally  diffused  but  impalpable 
medium  called  by  scientists  "ether." 

The  waves  or  oscillations  are  electrical  and  optical  in  their  nature, 
and  have  certain  properties  similar  to  "light"  waves  in  that  they  can 
be  reflected,  refracted,  and  defracted,  and  travel  at  the  same  speed  as 
"light"  waves.  Unlike  an  electric  current  (so  called)  the  oscillations  do 
not  flow  from  the  source  of  current  over  or  through  a  conductor,  but 
detach  themselves  or  radiate  from  the  place  or  instrument  of  produc- 


56 


MARCONI    INSTITUTE 


tion,  and  travel  through  space  as  light  does  from  the  sun,  or  as  sound 
does  from  a  bell. 

A  device  by  which  Maxwell's  predictions  were  confirmed  is  known 
as  the  "Hertz  Oscillator."  It  was  then  found  that  it  was  possible  to 
detect  the  existence  of  these  waves  by  employing  a  loop  of  wire,  with 
the  ends  brought  close  together ;  if  this  little  loop  of  wire  had  a  certain 
relation  to  the  direction  along  which  the  wraves  ought  to  be  traveling, 


&ETICTQR 


POTENTIOMETER 


A  special  compact  receiving  set  had  to  be  designed  for  use  with 
the  %  K.  W.  transmitter.  The  photograph  shows  the  type  112  receiving 
tuner  of  the  American  Marconi  Company  which  contains  full  appliances 
for  tuning  and  for  adjustment  of  the  receiving  detector.  This  tuner 
has  a  range  from  200  to  3,000  meters  and  is  characterized  by  simplicity 
throughout. 

minute  sparks  could  be  detected  between  the  ends  of  the  loops.  This 
little  loop  of  wire  is  called  a  "Hertz  resonator." 

These  experimental  researches  aroused  great  interest  in  the  scien- 
tific world.  In  1889  Sir  Oliver  Lodge  continued  the  experiments  on 
a  somewhat  larger  scale,  and  even  connected  the  oscillator  to  a  wire 
fence.  In  1890  a  distinguished  French  scientist,  Edouard  Branly,  pub- 
lished an  article  describing  a  great  variety  of  substances,  which  he  had 
discovered  to  be  sensitive  to  Hertz  waves,  that  is  by  means  of  these 
substances  he  could  detect  the  presence  of  these  waves. 

In  the  year  1892,  following  the  publication  of  Branly 's  discoveries, 


MARCONI    INSTITUTE 


57 


an  eminent  English  scientist,  Sir  William  Crookes,  published  his  famous 
prophecy  in  the  Fortnightly  Review  entitled  "Some  Possibilities  of 
Electricity."  Crookes  referred  to  the  before  mentioned  researches  and 
predicted  that  eventually  means  would  be  discovered  for  transmitting 
signals  in  code.  Crookes  said  that  this  was  no  mere  dream  of  a  visionary 
philosopher,  but  all  the  requisites  needed  to  bring  it  within  the  grasp 
of  daily  life  were  well  within  the  possibility  of  discovery,  and  were  so 
reasonable  and  so  clearly  in  the  path  of  researches  which  were  then 


oOOo 


OOQ 


The  photograph  shows  the  station  type  of  wave  meter  and  decre- 
meter  developed  by  the  American  Marconi  Company.  This  apparatus 
permits  the  transmitting  and  receiving-  apparatus  to  be  calibrated  in 
wave  lengths  and  is  useful  for  special  radio  frequency  measurements 
such  as  the  determination  of  the  inductance  and  capacity  of  a  circuit. 
It  is  also  employed  for  measuring  the  logarithmic  decrement  of  damp- 
ing. 

being  actively  prosecuted  in  every  capital  of  Europe,  that  one  might 
any  day  expect  to  hear  that  they  had  emerged  from  the  realms  of  specu- 
lation into  those  of  sober  fact.  This  remarkable  prophecy  was 
completely  fulfilled  by  Marconi,  as  we  now  know. 

In  the  following  year,  1893,  Nicola  Tesla  delivered  lectures  before 
the  Franklin  Institute  in  Philadelphia  and  before  the  National  Electric 
Light  Association  at  St.  Louis,  on  the  subject  of  High  Frequency  and 
High  Potential  Currents.  Tesla  was  not  dealing  with  Hertzian  waves, 
but  after  discussing  and  describing  certain  apparatus  for  high 
frequency  illumination  and  power  transmission,  he  referred  to  the 
possibility  of  the  transmission  of  intelligible  signals,  or  perhaps  even 


58  MARCONI    INSTITUTE 

power,  at  any  distance,  without  the  use  of  wires.  Tesla  said  that  he 
knew  that  the  great  majority  of  scientific  men  would  not  believe  that 
such  results  could  be  practically  and  immediately  realized,  but  he  was 
firmly  convinced  that  it  could  be  done  and  he  hoped  they  would  all  live 
to  see  it  done. 

In  1894  Sir  Oliver  Lodge  published  a  series  of  articles  in  the 
London  Electrician  on  the  work  of  Hertz,  and  described  various  forms 
of  detectors  or  receivers  which  would  render  manifest  the  existence  of 
Hertzian  waves.  Some  of  these  detectors  were  discoveries  of  his  own 
and  others  were  repetitions  of  Branly's  discoveries. 

In  1895,  a  Russian  scientist,  Professor  A.  S.  Popoff,  in  a  lecture 
delivered  and  printed  in  the  Journal  of  the  Russian  Physical  Chemical 
Society  repeated  some  of  the  experiments  of  Branly  and  Lodge,  and 
also  gave  an  account  of  some  experiments  of  his  own  relative  to  certain 
substances  which  he  had  noted  were  detectors  of  the  waves.  In  this 
article  Popoff  also  described  an  experiment  which  he  had  made  at  a 
laboratory,  in  which  he  noted  that  if  one  of  his  detectors,  consisting  of 
a  Branly  tube  containing  filings,  was  connected  to  a  lightning  conductor 
at  one  end  and  to  the  ground  at  the  other,  with  an  electric  bell  and  bat- 
tery in  circuit,  the  existence  of  a  distant  thunder  storm  in  the  Ural 
mountains  could  be  noted.  He  concluded  his  paper  by  expressing  the 
hope  that  with  further  improvements  and  the  discovery  of  a  source  of 
vibrations  possessing  sufficient  energy,  his  apparatus  might  be  adapted 
to  the  transmission  of  signals  at  a  distance. 

The  period  from  the  middle  of  the  nineteenth  century  until  1896 
thus  forms  a  period  of  speculation. 

To  recapitulate:  Maxwell,  in  1863,  had  speculated  on  the  possibility 
of  the  production  of  electric  waves  which  would  detach  themselves  from 
the  source  of  origin;  Hertz,  in  1887,  had  proved,  experimentally,  that 
Maxwell's  theories  were  correct;  Lodge,  in  1889,  repeated  these  experi- 
ments; Branly,  in  1890,  discovered  that  certain  substances,  in  addition 
to  Hertz's  ring  resonator,  were  detectors  of  electric  waves ;  Crookes,  in 
1892,  had  dreamed  of  the  possibility  of  wireless  telegraphy  by  utiliza- 
tion of  the  waves.  In  1893  Tesla  was  experimenting  with  older 
methods  and  was  giving  thought  to  the  matter.  Lodge,  in  1894,  had 
repeated  the  original  experiments  and  some  others  of  his  own  touching 
upon  the  form  which  these  electric  waves  took  when  emanating  from 
their  source  of  origin.  He  also  experimented  upon  substances  which 
would  detect  these  waves.  Popoff,  in  1895,  had  done  the  same  and 


MARCONI    INSTITUTE  59 

noted  that  he  could,  by  reason  of  certain  substances,  detect  the 
existence  of  a  distant  thunder  storm,  and  expressed  the  hope  that  wire- 
less telegraphy  would  be  accomplished.  But  no  one  had  described  or 
illustrated  a  system  of  wireless  telegraph  apparatus  adapted  for  the 
transmission  and  reception  of  definite,  intelligible  signals  by  means  of 
Hertzian  waves. 

MARCONI'S  DISCOVERY 

In  1896  the  lay  and  scientific  world  was  astounded  at  the  announce- 
ment that  the  hope  of  Popoff  and  the  dream  of  Crookes  had  been 
fulfilled  in  the  successful  transmission,  to  a  distance,  of  intelligible 
Morse  signals  through  space  by  means  of  Hertz  waves,  without  the  use 
of  connecting  wires,  and  that  a  heretofore  unknown  Italian  inventor 
by  the  name  of  Guglielmo  Marconi  had  successfully  discovered  and 
invented  means  for  accomplishing  this  astounding  and  wonderful  result. 

It  was  very  evident  that  he,  who  first  harnessed  these  peculiar  mani- 
festations and  produced  a  system  whereby  they  could  be  molded  into 
definite  and  predetermined  signals,  found  means  of  efficiently  propagat- 
ing them  to  a  distance,  and  provided  means  for  their  intelligible 
reception  at  distant  points,  had  made  a  most  remarkable  invention. 

By  what  means,  then,  did  Marconi  attain  such  a  marvelous  achieve- 
ment ? 

The  system  invented  by  Marconi  consisted,  essentially,  of  a  signal 
apparatus  at  a  sending  or  transmitting  station,  for  controlling  in  a 
definite  way  the  spark  gap,  and  causing  it  to  produce  Hertzian  waves 
of  definite  form,  character  and  duration,  and  sparking  apparatus  sub- 
ject to  nice  control  and  means  for  radiating  and  propagating  the  waves 
so  produced  through  the  ether  to  another  distant  station,  known  as  the 
receiving  station,  where  they  were  received  and  caused  to  manifest 
themselves  through  the  medium  of  suitable  apparatus,  as  telegraphic- 
signals  and  messages. 

The  story  of  Marconi's  early  work,  in  1894  and  1895,  on  his  father's 
estate  at  Bologna  is  of  intense  interest,  but  for  the  sake  of  brevity  will 
not  be  told  here. 

THE  ASTOUNDING  RESULTS  WHICH  HAVE  BEEN  ACHIEVED  BY 
THE  MARCONI  INVENTION 

The  Government  of  Great  Britain  owns  and  operates  all  land  tele- 
graph systems,  and  early  in  1896,  Mr.  Marconi  demonstrated  to  the 
satisfaction  of  Sir  William  H.  Preece,  the  Chief  Engineer  of  the  British 
Post  Office,  that  his  invention  had  then  achieved  what  no  other  scientist 


MARCONI    INSTITUTE  61 

or  physicist  before  him  had  been  able  to  achieve,  namely,  the  trans- 
mission of  intelligible  signals  by  means  of  Hertz  waves,  and  to  receive 
them  as  such,  at  a  distance,  without  wires.  Officers  of  the  British 
Government  were  instructed  to  witness  these  demonstrations  in  London, 
which  were  so  successful  that  the  British  Government  invited  Mr. 
Marconi  to  carry  out  further  demonstrations  before  officers  of  the 
British  Navy,  the  British  Army,  and  the  British  Post  office,  at  Salis- 
bury Plain,  some  eighty  miles  from  London,  in  September,  1896.  At 
these  demonstrations  the  British  Government  was  satisfied  that  trans- 
mission over  a  distance  of  1%  miles  was  achieved. 

The  early  history  of  the  development  of  the  invention  from  1896 
onward  records  ever  increasing  achievement  in  distance  of  transmission, 
until  as  early  as  1910  a  distance  of  over  6,000  miles  was  attained,  from 
a  station  at  Clifden,  Ireland,  to  another  station  at  Buenos  Aires,  in 
the  Argentine  Republic. 

These  new  and  astonishing  results  attained  by  Marconi  made  his 
an  epoch-making  invention. 

After  Marconi's  demonstrations  at  Salisbury  Plain  in  1896,  further 
demonstrations  were  carried  out  in  1897  before  representatives  of  the 
British  Post  Office  and  the  British  Navy,  when  the  distance  was 
increased  to  four  miles,  and  in  the  same  year,  before  officers  detailed  by 
the  British  Navy,  the  British  Army,  and  the  British  Post  Office,  as  well 
as  the  British  Board  of  Trade,  to  witness  the  demonstrations,  com- 
munication was  successfully  established  over  a  distance  of  nine  miles 
across  the  Bristol  Channel. 

The  success  achieved  by  Mr.  Marconi  in  this  early  work,  done  at 
the  invitation  of  the  British  Government,  attracted  the  attention  of 
other  Governments.  Professor  Slaby  of  Berlin  witnessed  these  remark- 
able demonstrations  and  was  shown  the  apparatus  by  means  of  which 
these  marvelous  results  were  achieved.  At  the  conclusion  of  the  demon- 
strations Professor  Slaby  went  back  to  Germany  and  in  an  address 
described  what  he  had  seen  as  a  great  discovery. 

Later,  in  1897,  Mr.  Marconi  demonstrated  the  new  telegraph  to 
the  Italian  Government,  and  at  Spezia,  Italy,  he  installed  his  appa- 
ratus on  one  land  station  and  on  some  Italian  warships.  During  these 
demonstrations,  successful  communication  was  established  up  to  a 
distance  of  twelve  miles  and  the  official  report  by  the  Italian  Navy  De- 
partment, as  a  result  of  these  demonstrations,  contained  a  remarkable 
tribute  to  Marconi's  wonderful  invention, 


MARCONI   INSTITUTE  63 

Still  later,  in  1897,  Mr.  Marconi  returned  to  England  and  con- 
tinued further  demonstrations  before  the  British  Navy,  Army  and  Post 
Office  officials. 

Early  in  1898  stations  were  erected  at  "The  Needles,"  Isle  of 
Wight,  and  at  Bournemouth  on  the  mainland,  and  communication  was 
established  for  a  distance  of  over  fourteen  miles  between  these  two 
places.  ^jfj 

Also  in  1898  the  first  commercial  application  of  wireless  telegraphy, 
for  the  purposes  of  journalism,  was  made.  A  Dublin  (Ireland)  daily 
newspaper — The  Daily  Express — fitted  out  an  ocean-going  tug  with 
Marconi  apparatus,  and  by  means  of  that  installation,  and  a  similar 
installation  at  Kingston,  Ireland,  the  Kingston  yacht  races,  held  in  the 
Irish  Channel  that  year,  were  reported  by  wireless  telegraphy.  A  dis- 
tance of  twenty-five  miles  was  attained,  which,  at  that  time,  was  a  most 
remarkable  achievement. 

In  1899  communication  was  established,  for  the  first  time,  by  wire- 
less telegraphy,  between  England  and  France,  across  the  English  Chan- 
nel, the  distance  between  these  two  stations  being  thirty-two  miles. 

In  the  fall  of  1899  the  first  practical  application  of  wireless 
telegraphy  in  the  United  States  was  made  by  Mr.  Marconi  himself,  in 
carrying  out  an  agreement  with  the  New  York  Herald  to  report  the 
International  Yacht  Races,  held  off  Sandy  Hook. 

At  the  conclusion  of  these  International  Yacht  Races,  at  the  request 
of  the  United  States  Government,  Mr.  Marconi  equipped  the  armored 
cruiser  "New  York,"  the  battleship  "Massachusetts"  and  the  torpedo- 
boat  "Porter"  with  wireless  telegraph  apparatus,  and  several  officers 
were  detailed  to  investigate  his  apparatus  during  tests  conducted  on 
these  warships.  The  report  of  these  tests  which  was  contained  in  the 
Proceedings  of  the  United  States  Naval  Institute,  stated  that  communi- 
cation was  effected  between  the  warships  over  a  distance  of  forty-five 
miles. 

In  1900,  in  consequence  of  the  successful  tests  during  the  naval 
maneuvers,  the  British  Navy  entered  into  a  contract  to  equip  thirty-two 
of  its  ships  and  stations  with  Marconi  apparatus. 

Marconi  was  improving  his  apparatus  from  time  to  time,  in  order  to 
attain  still  greater  results,  and  in  1901  the  apparatus  was  installed  in 
the  United  States  on  the  Nantucket  Lightship. 

In  December  of  1901  he  transmitted  an  intelligible  signal  across  the 


64  MARCONI   INSTITUTE 

Atlantic,  between  Poldhu,  Cornwall,  England,  and  a  station  in  New- 
foundland. 

The  announcement  in  the  public  press  that  Mr.  Marconi  had 
successfully  telegraphed  across  the  Atlantic  by  wireless  telegraphy, 
aroused  the  utmost  astonishment  and  excitement.  The  Anglo-American 
Cable  Company  were  apparently  so  disturbed  that  they  started  a  suit 
against  Marconi,  asking  for  an  injunction  to  prevent  him  from  erecting 
a  permanent  station  in  Newfoundland,  on  the  ground  that  they  had  the 
exclusive  right  for  a  term  of  years  for  all  cable  stations  in  Newfound- 
land. 

A  considerable  number  of  articles  appeared  in  the  public  press  at 
this  time  and  reported  the  first  successful  transmission  of  intelligence 
across  the  Atlantic. 

In  the  next  month  Mr.  Marconi  was  given  a  complimentary  dinner 
by  the  American  Institute  of  Electrical  Engineers  in  New  York,  com- 
memorative of  his  wonderful  achievement  in  establishing  transatlantic 
communication  by  means  of  wireless  telegraphy.  Such  distinguished 
scientists  as  Steinmetz,  Elihu  Thomson,  Alexander  Graham  Bell,  and 
Dr.  Pupin  were  present.  Upon  this  occasion  Mr.  Marconi  was  accorded 
the  highest  scientific  recognition  of  his  marvelous  achievement.  Among 
the  eminent  scientists  who  sent  congratulatory  telegrams  were  Thomas 
A.  Edison  and  Nicola  Tesla. 

Next,  in  February,  1902,  Marconi  performed  extraordinary  receiv- 
ing experiments  aboard  the  American  Line  steamship  "Philadelphia," 
enroute  from  England  to  New  York.  At  that  time  he  received  messages 
over  a  distance  of  2,099  miles  from  the  station  at  Poldhu,  Cornwall  - 
In  July  of  the  same  year  signals  were  received  from  Poldhu  on  the 
Italian  battleship  "Carlo  Alberto"  when  lying  at  Kronstadt,  at  a  dis- 
tance of  1,600  miles  from  Poldhu. 

Shortly  afterward  the  long  distance  station  at  Cape  Cod,  Massa- 
chusetts, was  equipped  for  transatlantic  work  and  a  station  was 
erected  at  the  expense  of  the  Canadian  Government,  at  Cape  Breton, 
Canada.  A  transatlantic  message  was  despatched  from  Cape  Cod, 
Massachusetts,  to  Poldhu,  England,  on  January  19,  1903,  and  in  the 
same  year  the  first  International  Conference  on  wireless  telegraphy  was 
held  in  Berlin  for  the  formation  of  rules  to  govern  the  ship  operation 
and  shore  radio  stations  in  the  principal  countries. 

Great  stimulus  was  given  to  the  commercial  development  of  wireless 
telegraphy  in  the  United  States  from  the  year  1903  onward.  In  1907 


MARCONI    INSTITUTE  65 

the  Marconi  transatlantic  stations  at  Clifden,  Ireland,  and  Glace  Bay, 
Nova  Scotia,  were  opened  and  traffic  was  accepted  for  all  points  in 
England  and  Canada. 

Great  impetus  was  given  to  the  use  of  wireless  aboard  ship,  in  the 
year  1909,  by  the  collision  of  the  steamship  "Republic"  with  the  steam- 
ship "Florida"  off  the  coast  of  the  United  States.  Assistance  was 
called  for  through  the  wireless  equipment  on  the  "Republic"  which  was 
answered  by  vessels  within  range,  and  as  a  result  the  passengers  and 
crew  were  saved  before  the  vessel  sank.  This  was  by  no  means  the  first 
rescue  made  through  the  medium  of  wireless  telegraphy,  but  it  appar- 
ently made  a  greater  impression  on  ship  owners  than  any  previous 
similar  event. 

Then  came  Marconi's  record-breaking  transmission  of  messages 
between  Clifden,  Ireland,  and  Buenos  Aires,  Argentine  Republic,  a 
distance  of  over  6,000  miles. 

During  the  years  1910,  1911,  and  1912,  a  world-wide  development 
in  the  commercial  application  of  wireless  telegraphy  took  place.  All 
vessels  of  any  considerable  tonnage  throughout  the  civilized  world  were 
equipped  with  modern  radio  apparatus,  and  in  addition  shore  stations 
were  erected  at  the  principal  seaports.  By  means  of  a  system  of  com- 
munication charts,  prepared  by  the  Marconi  Company,  it  became 
possible  for  a  vessel  to  establish  communication,  by  relay,  with  a  land 
station  in  any  part  of  the  world.  Commercial  ship-to-shore  traffic 
increased  enormously  during  this  period,  and  as  steamship  owners 
realized  the  assurance  of  safety  to  vessels  and  cargo,  and  the  possible 
saving  of  human  life,  which  would  result  through  the  use  of  wireless 
telegraphy,  an  unprecedented  demand  for  ship  equipments  followed. 

Compulsory  legislation  was  then  enacted  by  the  great  nations,  com- 
pelling the  use  of  wireless  apparatus  on  ships  above  a  certain  tonnage. 
Not  only  was  the  installation  of  apparatus  required,  but  according  to 
the  regulations  of  the  International  Radio-Telegraphic  Convention,  to 
which  the  United  States  subscribed  in  the  year  1912,  the  wave  lengths 
employed  in  radiotelegraphy  for  ship  use  were  restricted.  It  was 
required  that  the  transmitting  apparatus  be  adjusted  to  radiate  a 
wave  of  different  length,  and  standards  were  also  adopted  for  the  char- 
acter of  the  radiated  wave. 

The  next  step  of  importance  in  the  commercial  application  of  wire- 
less telegraphy  was  the  completion  of  the  Marconi  Company's  high 
power  stations  at  Carnavon,  Wales,  and  New  Brunswick,  New  Jersey, 


66  MARCONI    INSTITUTE 

in  1914.  Stations  were  also  erected  between  Bolinas,  California,  and 
Kahuku,  on  the  Island  of  Oahu,  Hawaiian  Islands.  The  California- 
Honolulu  circuit  was  opened  to  public  service  in  September,  1914. 

About  this  time  the  German  Telefunken  Company  erected  a  high 
power  station  at  Sayville,  Long  Island,  to  communicate  with  a  similar 
station  at  Nauen,  Germany,  and  a  high  power  station  was  erected  by 
another  company  at  Tuckerton,  New  Jersey,  for  communication  with 
Hanover,  Germany. 

Practical  tests  of  radiotelegraphy  aboard  trains  were  made  in  1913 
by  Marconi,  and  in  1915  direct  wireless  telephonic  conversation  was 
effected  between  the  United  States  Government  station  at  Arlington, 
Virginia,  and  Honolulu,  in  the  Hawaiian  Islands.  A  little  later  wireless 
telephonic  conversation  was  held  between  Arlington,  Virginia,  and  Paris, 
France. 

During  the  period  1912  to  1917,  the  United  States  Navy  Depart- 
ment connected  all  its  important  naval  bases  by  radio. 

Progress  in  the  year  1917  may  not  yet  be  recorded,  for  the  greater 
part  of  the  development  during  that  period  was  on  behalf  of  the  various 
Governments  engaged  in  war. 


A  special  panel  receiving  set  was  also  designed  for  use  in 
ship  work.  The  photograph  shows  the  type  106  receiving  tuner 
of  the  American  Marconi  Company  which  is  complete  in  every 
detail.  It  has  a  range  of  wave  length  from  200  to  3,500  meters 
and  is  particularly  suitable  for  ship  traffic.  The  cabinet  con- 
tains the  component  parts  of  an  inductively  coupled  receiving 
transformer  with  all  accessory  apparatus  necessary  for  tuning 
and  adjusting.  The  tuner  also  includes  a  buzzer  tester  for 
preadjusting  the  crystal  to  its  most  sensitive  condition. 


SCIENTIFIC  PROGRESS 

FT  is  not  practicable  here  to  give  a  complete  resume  of  the  scientific 
•*•  progress  in  radio  during  the  past  seventeen  years,  but  some  of  the 
more  important  developments  will  be  briefly  noted. 

Marconi's  original  transmitter  consisted  of  an  induction  coil,  the 
secondary  of  which  was  connected  to  a  spark  discharge  gap.  One 
terminal  of  the  gap  was  connected  to  a  vertical  insulated  wire  and  the 
opposite  terminal  to  earth.  Marconi's  early  receiver  consisted  of  a 
glass  tube  fitted  with  metal  lugs  on  either  end  between  which  was  placed 
a  small  quantity  of  metallic  filings.  This  device,  known  as  a  "coherer," 
was  connected  in  series  with  a  telegraph  relay  and  a  battery.  One 
terminal  of  the  coherer  was  connected  to  the  aerial  wire  and  the  other 
to  earth. 


This  photograph  shows  the  rear  view  of  the  type  106  re- 
ceiving tuner,  in  which  can  be  seen  the  primary  and  secondary 
coils  of  the  oscillation  transformer,  the  shunt  secondary  and 
the  aerial  condenser  and  the  special  rack  and  pinion  for 
changing  the  coupling  between  the  primary  and  secondary  coils. 

Under  the  influence  of  the  electrical  oscillations  induced  into  the 
coherer  circuits  by  the  distant  transmitter,  the  conductivity  of  the 
filings  instantly  increased,  closing  a  battery  circuit  through  the 
telegraph  relay.  A  vibrating  hammer  device  known  as  a  de-coherer 
tapped  the  coherer  at  the  termination  of  each  signal  and  placed  it  in 
condition  to  become  responsive  to  the  next  impressed  group  of  oscilla- 
tions. 

Marconi  next  improved  the  transmitter  provided  for  removing  the 
spark  gap  from  the  antenna  circuit,  placing  it  in  a  local  or  closed  cir- 
cuit, which,  on  account  of  the  increase  of  capacity  over  that  of  the 
aerial  wires,  generated  more  powerful  oscillations.  Then  by  means  of 

67 


68  MARCONI    INSTITUTE 

an  oscillation  transformer,  these  locally  generated  radio-frequency 
currents  were  transferred  to  the  antenna  or  radiating  wires. 

This  change  in  design  resulted  in  more  powerful  radiation  from  the 
transmitter  aerial  with  less  damping  of  the  oscillations,  which  reduced 
the  interference  between  stations.  Increased  freedom  from  interference 
was  also  obtained  at  the  receiver  by  coupling  the  coherer  circuit  to  the 
aerial  wires  through  a  specially  designed  receiving  transformer. 

It  is  fully  established  that  Marconi  was  the  first  to  realize  the  neces- 
sity for  complete  resonance  between  the  transmitter  and  the  receiver. 
His  original  "four  circuit  tuning"  patent  covering  this  principle  has 
become  famous  throughout  the  world,  and  its  claims  have  been  sustained 
in  the  major  courts  wherever  contested.  This  patent  was  filed  in  Eng- 
land, April  26,  1900. 


Marked  improvement  was  made  in  receiving-  apparatus  in  the  United  States 
during  the  years  1912-1913.  The  component  parts  of  a  receiving1  set  were  mounted 
compactly  in  a  cabinet  and  all  control  switches  mounted  on  a  panel  directly  in 
front  of  the  operator  where  they  were  easily  accessible. 

The  photograph  shows  the  type  101  receiving  tuner  of  the  American  Marconi 
Company  which  has  a  range  of  from  300  to  7,500  meters.  It  is  fitted  with  a  car- 
borundum and  cerusite  detectors  and  further  contains  a  complete  set  of  tuning 
appliances  for  the  primary  and  secondary  circuits.  This  receiver  is  acknowledged 
by  experts  to  be  the  most  complete  of  its  type. 

Sir  Oliver  Lodge  made  a  number  of  investigations  during  Marconi's 
early  work  and  he  was  instrumental  in  developing  a  special  system  in 
collaboration  with  Dr.  Muirhead.  Lodge  filed  one  basic  patent  owned 
by  the  Marconi  Co.  on  loaded  aerials  which  proved  valuable. 

Another  important  invention  of  Marconi's  was  the  perfection  of 
the  magnetic  detector  which  depended  for  its  operation  upon  the 
ability  of  high-frequency  currents  to  demagnetize  a  moving  band  of 
iron  under  the  influence  of  permanent  magnets.  This  detector  permit- 


MARCONI    INSTITUTE  69 

ted  the  use  of  a  telephone  receiver  in  place  of  the  telegraph  relay  for 
recording  signals,  and  it  allowed  practically  unlimited  speed  of  recep- 
tion. 

The  use  of  the  telephone  receiver  marked  a  distinct  gain  in  the  com- 
mercial progress  of  radiotelegraphy,  because  it  permitted  the  operator 
to  distinguish  between  radio  signals  sent  out  by  a  distant  transmitter, 
and  the  interfering  sounds  of  atmospheric  electricity  which  differed 
in  tone. 

The  induction   coil   as   a  source   of  high   voltage   current   for  the 


The  development  of  the  Multiple  Plate  Spark  Discharge  Gap  in  the 
year  1908  increased  the  efficiency  of  low  power  spark  transmitters  to  a 
marked  degree.  The  gap  proved  eminently  practical  for  ship  use  as  it 
removed  the  great  objection  to  open  spark  dischargers — the  crashing 
noise  which  sometimes  did  not  prove  particularly  pleasing  to  the  pas- 
sengers' ears. 

The  photograph  shows  a  2  K.  W.  and  1  K.  W.  discharger  of  the 
early  type.  These  were  substituted  in  the  closed  oscillation  circuit  for 
the  regular  spark  gap.  In  addition  to  the  cooling  afforded  by  the 
flanges  of  the  copper  plates,  a  blast  of  air  from  a  fan  or  blower  was 
constantly  directed  against  the  cooling  flanges. 

transmitter  was  early  replaced  by  Marconi  and  other  investigators  with 
the  high  voltage  alternating  current  transformer.  Alternating  current 
for  the  commercial  operation  of  radio  sets  was  introduced  in  the  United 
States  during  the  years  1901  and  1902. 

Investigators  were  entering  the  field  and  endeavoring  to  discover 


70  MARCONI    INSTITUTE 

more  sensitive  means  than  the  coherer  for  detecting  radio  currents. 
The  electrolytic  detector  attributed  to  Fessenden  in  the  United  States 
and  Schloemilch  in  Germany,  was  tried,  but  gave  way  lo  the  crystal 
detector  and  valve  detectors  to  be  referred  to. 

The  advantages  of  the  high-frequency  spark  discharger  were  early 
recognized  both  in  the  United  States  and  abroad,  and  during  the  years 
1903  to  1905,  transmitters  operated  by  125  and  133  cycle  current 
were  widely  introduced  in  the  United  States. 


The  desirability  of  musical  tones  at  the 
transmitter  was  early  recognized  in  the  art 
of  wireless  telegraphy  because  it  permitted 
the  receiving  operator  to  distinguish  between 
the  discharges  of  atmospheric  electricity  and 
the  signals  sent  out  by  a  distant  transmitter. 
Also  it  permitted  greater  ease  of  formation 
of  the  code  characters.  In  order  to  produce 
a  musical  tone  from  60  cycle  transmitters,  the 
non-synchronous  rotary  discharger  shown  in 
the  photograph  was  designed.  With  this  gap, 
240  sparks  per  second  were  obtained  from  the 
transmitter  supplied  with  60  cycle  alternat- 
ing current.  This  gap  also  aided  the  quench- 
ing of  the  primary  oscillations  and  thereby 
produced  a  radiated  wave  of  greater  purity. 

The  principal  advantage  of  the  high  frequency  spark  lav  in  the 
fact  that  it  enabled  the  receiving  operator  to  distinguish  radio  signals 
from  the  interfering  discharges  of  static  or  atmospheric  electricity. 

The  year  1905  saw  also  the  development  of  the  synchronous  rotary 
spark  discharger  for  the  transmitter. 

The  next  great  advance  in  respect  to  the  receiving  detectors   of 


MARCONI    INSTITUTE  71 

wireless  telegraphy  was  the  discovery  by  Professor  J.  Ambrose  Flem- 
ing, of  the  Marconi  Co.  in  England  in  1904,  that  if  a  metallic  plate  was 
sealed  within  the  bulb  of  an  incandescent  lamp  filament  and  the  plate 
and  filament  were  connected  to  the  secondary  of  a  receiving  transformer, 
the  device  became  a  very  sensitive  detector  of  high  frequency  oscilla- 
tions. The  discovery  of  this  fact  proved  to  be  the  foundation  work  for 
a  very  valuable  series  of  improvements  during  the  years  1912  to  1917. 
The  claims  of  Fleming's  patent  have  been  warmly  contested  in  the 
courts ;  but  in  every  case  the  inventor's  claims  were  fully  sustained. 

A  new  form  of  oscillation  detector  owned  by  the  Marconi  Co.  ap- 
peared in  the  year  1906.  It  was  invented  by  General  Dunwoody, 
U.  S.  A.,  who  discovered  that  a  crystal  of  carborundum  acted  very  effi- 
ciently as  a  receiver  for  electric  wave  telegraphy  and  it  was  found  later 
by  Professor  G.  W.  Pierce,  of  Harvard  University,  that  these  crystals 
possessed  the  property  of  rectification,  i.e.,  they  would  convert  a  high 
frequency  alternating  current  into  a  unidirectional  pulsating  current 
suitable  for  response  in  the  telephone  receiver.  Further  investigations 
by  Greenleaf  W.  Pickard  into  the  property  of  minerals  and  compounded 
crystals  revealed  that  galena,  silicon,  molbdenite,  iron  pyrites  and  others 
possessed  the  property  of  rectification  and  were  equally  suitable  as 
oscillation  detectors  for  wireless  telegraphy. 

One  form  of  oscillation  detector  introduced  at  this  period  was 
the  so-called  Perikon  detector,  a  trade  name  given  to  a  detector, 
consisting  first  of  a  crystal  of  zincite  in  contact  with  a  crystal  of  chal- 
copyrite  and  later  a  crystal  of  zincite  in  contact  with  one  of  bornite. 

Dr.  DeForest  in  1906  placed  a  grid  elerp-  4  \iween  the  filament 
and  the  plate  of  Fleming's  original  oscillatk  -  ,  alve,  and  he  named  his 
product  the  "audion." 

It  should  be  kept  in  mind  at  this  point  that  the  trend  in  the  early 
design  of  radio  transmitters,  particularly  in  the  United  States,  was 
towards  the  use  of  sets  of  low  power,  but  many  attempts  were  made  by 
the  Marconi  Company  in  England  in  1902,  and  at  South  Wellfleet,  in 
the  United  States,  to  employ  very  large  powers  of  the  order  of  15 
to  40  kilowatts.  Many  of  these  transmitters  lacked  the  efficiency 
that  was  expected  on  the  part  of  the  designer  and  a  rapid  reversion 
took  place  in  the  United  States  (in  1906)  to  transmitters  of  lower 
power  of  the  order  of  2  kilowatts.  These  sets,  however,  were  used 
almost  exclusively  for  marine  communication. 

Marconi's  Wireless  Telegraph  Company,  Ltd.,  of  England, 
attacked  with  great  vigor  the  problem  of  designing  high  power  trans- 


72 


MARCONI    INSTITUTE 


mitters  for  long  distance  wireless  communication.  The  first  fruits  of 
this  series  of  experiments  was  the  establishment  of  twenty-four-hour 
transatlantic  wireless  service  between  Glace  Bay,  N.  S.,  and  Clifden, 
Ireland  in  1907. 

For  the  first  time  in  the  history  of  the  art  Marconi  employed  at 
these  stations  high  voltage  direct  current  for  charging  a  battery  of 
condensers.  This  current  was  obtained  from  6,000  storage  cells  con- 
nected in  series,  which  in  turn  were  charged  by  three  5,000-volt  direct 
current  generators  connected  in  series.  By  the  use  of  a  high  speed 


100,000  CYCLE  ALTERNATOR 
SPEED    20,000  R.P.M. 


DIRECT  CURRENT  MOTOR 
HO  VOLT    2000  R.P.M. 


An  undamped  wave  generator  of  unusual  mechanical  electric  construction 
has  been  developed  by  the  General  Electric  Company.  The  machine  shown  in 
this  photograph  is  known  as  the  Alexanderson  Radio  Frequency  Alternator, 
which  generates  direct  from  the  armature  winding  current  of  frequencies  up  to 
100,000  cycles  per  second.  It  may  be  noted  that  although  the  speed  of  the  motor 
is  but  2,000  revolutions  per  minute  the  speed  of  the  alternator  through  a  special 
turbine  wheel  is  increased  to  20,000  revolutions  per  minute.  So  far,  this  machine 
has  generally  been  employed  for  laboratory  experiment,  but  larger  generators  of 
50  and  75  K.W.  have  been  designed  which  generate  radio  frequency  currents  up  to 
75,000  cycles  per  second.  It  has  been  proposed  to  employ  these  generators  for 
long  distance  radio  telegraphy  and  telephony. 

rotary  disc  discharger  perfect  musical  tones  were  secured  suitable  for 
telephonic  reception. 

Another  innovation  introduced  during  this  period  at  the  Glace  Bay 
and  Clifden  stations,  was  the  employment  of  air  at  atmospheric  pres- 
sures as  the  di-electric  medium  for  the  high  voltage  condenser. 

Early  in  the  development  of  radio  art,  it  was  suggested  that  the 
use  of  undamped  oscillation  transmitters  w^uld  materially  increase  the 
distances  of  transmission  and  permit  a  greater  degree  of  selectivity  at 
the  receiver. 


MARCONI    INSTITUTE  73 

Valdemar  Poulsen  in  1903  produced  improvements  on  Duddell's 
singing  arc,  perfecting  it  to  the  point  where  it  could  be  em- 
ployed to  generate  the  extremely  high  frequency  currents  necessary 
for  the  generation  of  electromagnetic  waves,  but  his  early  apparatus 
did  not  operate  with  the  stability  of  Marconi's  spark  discharger  and 
consequently  it  was  not  used  commercially  until  its  perfection  by  Ameri- 
can engineers  during  the  years  1908  to  1917.  High  powered  arc  trans- 
mitters of  30  to  100  kilowatts  have  been  employed  for  trans-Atlantic 
and  trans-Pacific  communication.  In  fact,  the  United  States  Navy  has 
in  use  at  present  arc  generators  of  350  kilowatts  capacity. 

Alexanderson,  of  the  General  Electric  Company,  during  the  years 
1914-1915-1916,  produced  a  75  kilowatt  machine  which  generated 
current  at  50,000  cycles  per  second.  This  machine  ran  at  reduced  speed 
and  thereby  eliminated  one  of  the  most  difficult  problems  encountered 
in  the  design  of  radio-frequency  alternators. 

Dr.  Rudolf  Goldschmidt,  of  Hanover,  Germany,  designed  in  1910  a 
high  frequency  alternator  which  was  a  departure  from  machines  of 
the  Alexanderson  type,  the  principal  point  of  difference  being  that 
Goldschmidt's  alternator  generated  current  at  frequencies  up  to  60,000 
cycles  per  second  from  an  armature  which  revolved  at  a  speed  of  3,000 
R.P.M.  With  this  machine  successful  communication  was  established 
between  Tuckerton,  N.  J.,  U.  S.  A.,  and  Eilvese,  near  Hanover,  Ger- 
many, in  1913. 

About  the  time  that  Goldschmidt  was  engaged  on  his  alternator, 
Joly,  and  Count  Arco  of  Berlin  (1912)  evolved  a  system  for  increasing 
externally  to  the  generator  the  frequency  of  a  comparatively  low  radio 
frequency  alternator,  and  so  successful  were  their  first  experiments  that 
communication  was  established  between  Nauen,  Germany,  and  Sayville, 
L.  L,  U.  S.  A. 

During  the  period  that  the  efforts  of  scientists  were  engaged  upon 
the  problem  of  undamped  oscillations  transmitters,  progress  was  nmde 
in  the  spark  discharge  type  of  apparatus.  It  was  found  that  by  proper 
design  of  the  spark  gap,  quenching  effects  were  obtained  which  pre- 
vented the  reaction  of  the  antenna  circuit  upon  the  spark  gap  circuit. 
This  interchange  of  energy  ordinarily  caused  the  radio  transmitter  to 
emit  two  waves,  but  the  quenched  type  of  spark  dischargers  permitted 
the  antenna  to  oscillate  at  its  own  frequency  resulting  in  the  radiation 
of  a  single  wave. 

About  the  year  1908-1909,  what  is  known  as  the  multiple  plate  dis- 


74  MARCONI    INSTITUTE 

charger  appeared  in  the  radio  field  and  it  soon  had  universal  application 
transmitters  up  to  10  kilowatts  and  later  to  50  kilowatts. 

R.  H.  Armstrong  revealed  that  the  vacuum  valve  detector  pos- 
sessed the  property  of  repeating  radio  frequency  oscillations  into  its 
local  battery  or  telephone  circuit,  and  hence  by  coupling  this  circuit 
back  to  the  grid  circuit,  the  incoming  oscillations  were  magnified  several 
hundred  times.  A  most  noteworthy  increase  in  sensitiveness  was 
obtained.  Several  other  investigators,  among  whom  may  be  mentioned 
Roy  A.  Weagant,  chief  engineer  of  the  Marconi  Wireless  Telegraph 
Company  of  America,  found  that  a  three-element  vacuum  valve  with 
proper  accessories  became  a  generator  of  high  frequency  oscillations 
and  could  be  employed  to  produce  the  heterodyne  effect  first  disclosed 
by  Fessenden.  These  experimenters  employed  the  vacuum  valve  as  a 
combined  oscillator,  amplifier,  and  "beat"  receiver,  all  these  actions 
taking  place  simultaneously  within  the  same  bulb. 

H.  J.  Round,  of  the  Marconi  Co.  in  England,  who  performed  impor- 
tant experiments  in  this  direction  in  1913  and  1914,  produced  a  vacuum 
valve  oscillator  of  sufficient  power  output  at  radio  frequencies  to  carry 
on  radio  telephonic  and  radio  telegraphic  communication  over  consider- 
able distances. 

Various  methods  of  applying  vacuum  valve  bulbs  to  radio- 
telegraphy  have  been  perfected  during  the  year  1916.  These  bulbs 
have  been  used  in  a  battery  as  a  source  of  radiofrequency  current,  as 
a  means  of  amplifying  the  output  of  a  radio-frequency  alternator,  and 
as  a  means  of  controlling  the  antenna  current  from  such  an  alternator. 
At  the  receiving  station  the  vacuum  valve  is  employed  singly  for 
regenerative  amplification  or  in  the  cascade  for  radio-frequency  or  audio 
frequency  amplification.  They  also  have  been  extensively  employed  as 
repeaters  on  long  distance  wire  telephone  lines. 

In  the  summer  of  1916  Marconi  installed  at  Carnarvon,  Wales,  his 
timrd  spark  transmitter  which  generates  continuous  oscillations  by 
overlapping  wave  trains  in  the  antenn0  Circuit.  Very  successful  results 
were  obtained,  perfect  communication  ,  .. /ing  been  established  with  the 
American  Marconi  Company's  High  Power  Stations  at  Chatham, 
Massachusetts,  and  New  Brunswick,  New  Jersey. 

Inventions  are  now  in  process  of  perfection  that  will  practically 
eliminate  every  obstacle  that  heretofore  hindered  twenty-four-hour  long 
distance  radio  con  mnication,  and  it  is  safe  to  predict  at  the  close  of 
the  World  war,  a  commercial  expansion  in  the  art  will  take  place  such 
as  heretofore  was  not  considered  possible. 


MARCONI    INSTITUTE 


75 


Very  powerful  types  of  transmitting-  apparatus  are  required 
for  use  aboard  battle  ships.  The  photograph  shows  a  special  5 
K.  W.  quenched  spark  transmitter  developed  by  the  American 
Marconi  Company  for  naval  use.  This  transmitter  is  designed 
for  rapid  change  in  wave  lengths  and  also  permits  a  wide  varia- 
tion of  power. 


76  MARCONI    INSTITUTE 

THE  INSTITUTE  OF  RADIO  ENGINEERS 

ORGANIZED  IN  1912.  INCORPORATED  IN  1913. 

The  Institute  of  Radio  Engineers  is  today  the  only  American 
society  of  the  radio  engineering  profession.  Previous  to  its  formation 
the  two  most  influential  organizations  in  this  field  of  endeavor  were 
The  Society  of  Wireless  Telegraph  Engineers,  organized  in  1907,  and 
The  Wireless  Institute,  organized  in  1909.  Greater  effectiveness  was 
secured  through  their  consolidation  on  May  13,  1912,  into  The  Insti- 
tute of  Radio  Engineers.  Engineers,  experimenters  and  professional 
operators  are  kept  in  touch  with  the  technical  progress  of  the  radio 
art  through  its  Proceedings. 

This  organization  is  under  the  direction  of  the  foremost  radio 
experts  in  the  United  States  and  its  papers  record  the  development  of 
the  radio  art  throughout  the  world. 

The  Proceedings  of  the  Institute  are  under  the  editorial  direction 
of  Professor  Alfred  N.  Goldsmith  of  the  College  of  the  City  of  New 
York. 

Meetings  of  the  Institute  are  held  in  New  York  monthly  for  the 
presentation  and  discussion  of  engineering  papers.  These  papers  are 
presented  by  members  who  have  specialized  in  some  division  of  the  art 
and  who  desire  to  lay  their  results  before  the  radio  profession. 

Sectional  meetings  of  the  Institute  are  held  each  month  in  Boston, 
Washington,  and  San  Francisco. 

The  Institute  membership  consists  of  Associates,  Members,  and 
Fellows.  Qualification  for  these  classes  of  membership  are  in  accord- 
ance with  experience  and  achievement.  Students  of  the  art  who  seek 
for  later  professional  advancement  are  advised  by  the  directors  of  the 
Marconi  Institute  to  place  their  application  for  admission  as  Associates 
at  the  commencement  of  their  studies. 

Particulars  can  be  obtained  from  the  secretary. 

INSTITUTE  OF  RADIO  ENGINEERS, 

College  of  the  City  of  New  York,  New  York  City. 


MARCONI    INSTITUTE  77 

NATIONAL  WIRELESS  ASSOCIATION 

Founded  to  promote  the  best  interests  of  radio  communication  among  wireless  amateurs 

in  America 

GUGLIELMO  MARCONI,  President 

J.   ANDREW   WHITE,   Acting  President  ALONZO   FOGAL,   JR.,   Secretary 

NATIONAL    ADVISORY    BOARD    OF    VICE-PRESIDENTS 

Major   General   GEORGE   O.  Prof.    ALFRED    N.    GOLD-  Prof.  CHARLES  R.  CROSS 

SQUIER,     Chief    Signal                   SMITH,    College    of   the  Massachusetts      Institute 

Officer,  U.   S.  Army                           City   of   New   York  of  Technology 

Commander     D.     W.    TODD  fnr.t    w     T-T     r     "RTTT  T  AT?r> 

U.S.N.,    Director    Naval  C  P  n    S    N  Colonel    SAMUEL    REBEE 

ProfCOAmmEUnrEtN&SELLY  ELMER  E.  BUCHER  %g  C^<  U'  S' 

Harvard  University  Instructing    Engineer 

Major    WILLIAM     H.     EL-  Prof.    SAMUEL   SHELDON  WILLIAM   H.   KIRWIN 
LIOTT,     Junior     Ameri-                   Brooklyn  Polytechnic  In-  Chief     of     Relay      Corn- 

can  Guard  stitute  munications 

Headquarters,  25  Elm  St.,  New  York 

It  is  estimated  that  previous  to  the  United  States  entering  the  Wai- 
there  were  at  least  100,000  amateur  wireless  stations  in  active  opera- 
tion. 

Realizing  the  necessity  for  co-operation  among  amateur  experi- 
menters, ar  National  Association  was  formed  in  November,  1915,  with 
objects  which  are  summarized  as  follows: 

(1)  To  help  existing  radio  clubs  to  establish  more  effec- 
tive organizations  conducted  on  standardized  lines; 

(2)  To  stimulate  interest  in  the  formation  of  radio  clubs 
in  communities  where  there  are  a  few  amateurs; 

(3)  To  provide  authoritative  wireless  literature  for  ex- 
perimenters' use; 

(4)  To  establish  closer  connection  between  amateur  ex- 
perimenters and  military  organizations; 

(5)  To  organize  all  amateurs  in  the  United  States  for 
the  Government  in  time  of  war. 

(6)  To  establish  amateur  wireless  relay  routes  across  the 
United  States  as  an  auxiliary  in  event  of  loss  of  wire  com- 
munication; 

(7)  To  protect  the  amateur  purchasing  equipment  from 
unscrupulous  manufac turers ; 

(8)  To  keep  the  field  informed  on  current  legislation. 

A  Monthly  Service  Bulletin  has  been  published,  giving  amateurs 
the  latest  list  of  calls  of  licensed  stations  throughout  the  United  States, 
and  summarizing  the  most  recent  scientific  developments  in  the  radio 
art.  This  bulletin  was  later  transferred  to  the  pages  of  The  Wireless 
Age,  through  which  the  members  are  kept  in  close  touch  with  the  organ- 
ization. 


78  MARCONI    INSTITUTE 

By  co-operation  with  military  organizations  opportunity  has  been 
afforded  to  members  to  enter  military  encampments  during  the  sum- 
mers of  1916  and  1917,  where  they  were  taught  military  tactics  and 
instructed  in  field  radio  signaling.  The  number  instructed  in  camps 
for  the  two  seasons  is  1,126. 

The  Association's  large  membership  is  distributed  throughout  the 
United  States,  and  is  representative  of  the  most  advanced  experimenters 
in  the  field.  Several  hundred  are  now  in  the  Government  service  for  war 
work. 

Although  the  operations  of  the  amateur  experimenter  have  been 
temporarily  curtailed,  the  organization  is  continued  in  the  interest  of 
more  advanced  work  and  study.  The  membership  has  been  extended 
to  include  radio  workers  throughout  the  world. 

Membership  in  the  National  Wireless  Association  is  open  to  all 
radio  workers  who  seek  a  means  of  keeping  in  touch  with  their  fellow 
experimenters. 

The  Association  supplies  its  members  with: 

(1)  Home  training  courses  of  study; 

(2)  Representative  wireless  literature  of  the  day; 

(3)  Instructions  for  building  the  latest  types  of  transmit- 
ting and  receiving  apparatus; 

(4)  Solutions  of  problems  in  the  Bulletin  and  answers  queries 
in  the  official  organ  and  affords  him  opportunities  to  join 
commercial  companies. 

Fees. — The  initiation  fee  is  $1,  for  which  the  amateur  secures  a 
certificate  of  membership,  a  membership  button  and  an  aerial  pennant. 
The  annual  dues  are  $2.     For  this  members  receive : 

(1)  The  Wireless  Age  for  one  year,  which  includes  the 
Monthly  Service  Bulletin; 

(2)  The  book,  "How  to  Conduct  a  Radio  Club"; 

(3)  A  question  and  answer  volume,  "How  to  Pass  U.  S. 
Government  Wireless  License  Examinations"; 

(4)  A  discount  of  10  per  cent  on  any  book  listed  in  the 
Wireless  Man's  Bookshelf  section. 

Those  interested  in  improving  the  status  of  the  amateur  experi- 
menter through  connection  with  the  foremost  radio  association  in  the 
United  States,  are  invited  to  communicate  with 

SECRETARY,  NATIONAL  WIRELESS  ASSOCIATION 
25  Elm  Street,  New  York  City 


EQUIPMENT 
SECTION 


0 


MARCONI    INSTITUTE 


Gasoline  Engine  Driven 
Radio  Power  Unit 

DESIGNED  TO  FURNISH  INDEPENDENT  POWER 


3553. 


The  Copely  Power  Unit  is  equivalent  to  an  independent  power 
plant,  including  the  prime  mover. 

In  the  Army  and  Navy  installations  where  emergency  units 
are  needed  that  can  be  operated  independent  of  any  other  source 
of  power,  it  is  a  perfect  solution  of  the  problem. 

It  is  equally  adapted  to  the  requirements  of  educational 
institutions  and  scientific  laboratories  which  do  not  want  to  go  to 
the  great  expense  of  installing  separate  power  plants. 

It  is  also  a  much  more  dependable  and  economical  solution  for 
mining  plants  and  lumber  camps  when  immediate  service  is  required . 

Write  for  particulars  to  SALES  OFFICE:  398  Fifth  Avenue,  New  York. 

COPELY  MANUFACTURING   COMPANY,   Newark,  N.  J. 


MARCONI    INSTITUTE  81 


MURDOCK  RADIO  APPARATUS 


The 

of  those  individually  interested  in  TRAINING  FOR 
RADIO  SERVICE  and  of  those  contemplating  the  in- 
auguration of  classes  for  this  purpose  is  directed  to  the 
selected  apparatus  which  we  can  supply  for  this  use. 

We  are  prepared  to  furnish 

Head  Telephones 
Transmitting  Keys 
Buzzers,  Etc., 

suitable  for  either  individual  or  class  installations,  all  of 
the  quality  which  has  won  for  our  product  the  commenda- 
tion of  those  who  know  good  instruments. 

Prompt  deliveries  of  needed  apparatus  is  a  note- 
worthy feature  of  our  service,  either  in  ordinary  times  or 
in  emergencies. 

Write  us  of  your  requirements  and  let  us  tell  you 
how  we  can  serve  your  special  needs.  Descriptions  and 
prices  of  all  apparatus  gladly  furnished. 

Especially  Note 

that  our  Head  Telephone  Set  No.  63  is  approved  by  the 
U.  S.  Navy  Department  for  Radio  Instruction,  and  is 
officially  designated  Type  CZ  291.  Thousands  of  these  sets 
are  now  in  use  in  the  Naval  Radio  Schools  and  in  many 
public  and  private  training  institutions.  The  Moral? 
Specify  MURDOCK  No.  63  Telephone  for  your  service. 

WM.  J.  MURDOCK  CO. 

63  Carter  St.  Chelsea,  Mass. 


82 


MARCONI    INSTITUTE 


Frank  B.  Perry  &  Sons 

RADIO  BLINKER 

(Reg.  U.  S.  Pat.  Office) 

SIGNAL  SET 


(Pat.  Sept.  4,  1917) 


For  Individual  Practice  and  Instruction  in  teaching  the  Inter- 
national or  other  Codes  you  will  find  the  genuine  Perry  Radio 
Blinker  Signal  Set  of  immense  value  to  your  students.  Our 
equipments  are  high  grade,  of  unique  and  compact  design,  and 
meet  the  requirements  not  only  of  the  teacher  for  class  room 
work  but  for  the  student  as  well  for  practice  at  home. 

Our  Navy  Type  CZ-67  is  self-contained,  of  the  same  design 
adopted  by  the  Bureau  of  Steam  Engineering  and  made  to  Navy 
Dept.  specifications.  It  consists  of  a  high  grade  specially  wound 
adjustable  buzzer,  lamp  with  movable  protecting  metal  hood, 
sending  key  and  two-way  switch,  all  mounted  on  top  of  a  box 
containing  Eveready  battery  of  standard  type.  Dimensions 
5-5/16"  x  3-11/16"  x  3" ;  Weight  I  Ib.  6  oz. ;  Price  $5.00  postpaid. 

Our  Army  Type  RME-2,  as  illustrated,  is  of  the  same  general 
design  and  dimensions,  excepting  equipped  with  high  frequency 
specially  wound  buzzer  that  will  hold  its  adjustment  for  long 
periods,  and  also  with  binding  posts  for  making  connection  to 
telephone  head  receiver  if  desired.  Price  $6.50  postpaid. 

Some  of  our  large  users. 


Mass.  Institute  of  Tech. 
Princeton  University. 


U.  S.  Army  Schools  of  Aero- 
nautics 

Cambridge  Radio  School 
Boy  Scouts  of  America 

Write  for  special  prices  in 
lots  and  for  description  of  our 
other  models,  to  us  at  Newton 
Center,  Mass.,  or  to  our  li- 
censed manufacturers —  Stan- 
dard Paper  Box  Corp.,  Paw- 
tucket,  R.  I. 


Army  Type  RME-2 


FRANK  B.   PERRY  &  SONS 

Newton  Center,   Mass. 


MARCONI    INSTITUTE  83 

THOUSANDS  OF 

Edison  Army-Navy  Special 
Storage  Batteries 

are  in  extensive  use  by 

THE  RADIO  DIVISIONS 

of 
THE  UNITED  STATES 

and 
ALL  ALLIED  GOVERNMENTS 

because 
THE  EDISON 

is  the 

MOST  RUGGED 
MOST  PRACTICAL 

STORAGE  BATTERY  IN  THE  WORLD 


Our  New  Type  WI-T,  Army-Navy  Special  Edison 
Battery,  of  1  ]/£  ampere  hour  capacity,  very  small  and  of 
light  weight,  is  adopted  by  at  least  one  great  nation  as 
its  standard  for  operating  the  wing  circuit  of  electron 
relays. 

The  types  B-2  and  B-4  batteries  have  long  been  uni- 
versally conceded  as  being  the  best  obtainable  batteries 
for  operating  the  filament  circuit  of  electron  relays  and 
for  reserve  source  of  power  for  the  entire  radio  apparatus. 

Address 

MILLER-REESE-HUTCHISON,  Inc. 

Storage  Battery  Specialists  Orange,  N.  J. 

Branch  Office  at  1  6 1  8  1  8th  St.,  N.  W.,  Washington,  D.  C. 

Phone  North  3245 


MARCONI    INSTITUTE 


For  Instruction 
and  Active 


The  Indicating  Instruments  used  for  the  instruc- 
tion of  wireless  students  should  be  of  the  make 
and  type  that  will  be  encountered  later  in  practice. 


Electrical   Indicating   Instruments 

are  the  recognized  standard  instruments  of  the 
world  from  the  standpoints  both  of  scientific 
perfection  and  of  practical  serviceability.  Every 
consideration  recommends  their  use  in  connec- 
tion with  wireless  instruction. 

Weston    Electrical    Instrument    Co. 

131  Weston  Ave.,  Newark,  N.  J. 

23  Branch  Offices  in  the  Larger  Cities 


Weston  Round  Pattern  Switchboard  In- 
struments of  7-inch  diameter  are  the 
standard  for  use  on  Wireless  Telegraph 
Panels.  Write  for  more  specific  infor- 
mation. 


MARCONI    INSTITUTE  85 


In  Your  Wireless  Classroom 
and  Laboratory 

YOU  WILL  FIND  MANY  USES  FOR 

BAKELITE-DILECTO 


_ 

"'HE  standard  insulating  material 

for  all  radio  work.     Water-proof, 

permanent,  strong,  used  by  all  im- 

portant    manufacturers     of    wireless 

apparatus    and    others    requiring    the 

utmost  in  insulation. 

Furnished  in  sheets,  rods  and  tube. 

We  also  manufacture  vulcanized  fibre 
and  conite  for  special  insulating  pur- 
poses. 

Let  us  show  you  how  our  standard 

products    can   be    made    to    solve 

your  insulation  problems. 

THE  CONTINENTAL  FIBRE  CO. 

NEWARK,   DELAWARE 

233  Broadway,  New  York  City  3325  Michigan  Ave.,  Chicago,  111. 

525  Market  St.,  San  Francisco,  Cal.  411  S.  Main  St.,  Los  Angeles,  Cal. 

316  Fourth  Ave.,   Pittsburgh,  Pa. 

llllllilllllllllllllllllllllllllllllllllllllllllllllllllM 


86  MARCONI    INSTITUTE 


The  "JExibe"  Battery 
for  Wireless  Service 


Bulletin  No.  168  contains 
interesting  data  and  illustrations 
relating  to  the  "lExfbC"  Battery 
so  extensively  used  for  Wireless 
Service  and  Emergency  Lighting. 

Address  our  nearest  Sales 
Office  for  your  copy. 


"Exfoc* 


THE  ELECTRIC  STORAGE  RATTERYCO. 

The  Oldest  and  Largest  Manufacturer  of  Storage  Batteries  in  the  Country 

PHILADELPHIA,  PA. 

1888-1918 

New  York  Boston  Atlanta  Chicago  Denver 

St.  Louis  Cleveland  Rochester  Detroit  Toronto 

Washington  Pittsburgh  San  Francisco         Minneapolis  Kansas  City 


MARCONI    INSTITUTE 


MESCO  WIRELESS  PRACTICE  SETS 


"COMBINATION 


This  Practice  Set  consists  of  a  regular  telegraph  key 
without  circuit  breaker,  a  special  high  pitch  buzzer,  miniature 
lamp  socket,  lamp,  three  binding  posts,  switch  for  transferring 
current  from  lamp  to  buzzer,  all  mounted  on  a  polished  hard- 
wood base,  and  one  RED  SEAL  Dry  Battery  with  four  feet 
of  green  silk  covered  flexible  cord. 

The  efficiency  of  a  wireless  operator  is  gauged  by  his 
ability  to  read  both  sound  and  light  signals  and  this  practice 
set  offers  the  means  of  acquiring  proficiency  in  both,  for  the 
switch  is  used  for  connecting  either  the  buzzer  or  the  lamp 
into  circuit. 

The  set  is  of  exceptional  value  to  the  beginner,  as  it  may 
be  used  for  individual  code  practice  for  operation  on  a  two 
party  line.  After  the  beginner  has  mastered  the  code,  the 

set  may  be  used  for  his  wireless  outfit  for  setting  the  detector  into  its  most  sensitive  adjustment.     The  key 
also  may  be  used  to  control  the  spark  coil. 

The  sound  emitted  by  the  buzzer  simulates  the  tone  of  the  signals  of  the  most  modern  wireless  stations 
perfectly. 

This  outfit  is  particularly  recommended  for  schools  and  colleges  teaching  wireless  telegraphy  and  Morse 
or  Continental  visual  signaling,  as  it  gives  excellent  service  for  class  instruction  in   code  work. 
List  No.  Price 

52       MESCO    Combination    Practice    Set $3.60 

The  main   object   of  the   Mesco   Practice   Set  is  to   enable  "MESCO" 

the  beginner  to  learn  the  Morse  and  Continental  Codes, 
which  are  easily  mastered  as  the  buzzer  reproduces  the  sound 
of  the  signals  of  the  most  modern  wireless  stations  perfectly. 

It  comprises  a  regular  telegraph  key,  without  circuit 
breaker,  a  special  high  pitch  buzzer,  one  cell  RED  SEAL  Dry 
Battery,  and  four  feet  of  green  silk  covered  flexible  cord. 

The  key  and  buzzer  are  mounted  on  a  highly  finished 
wood  base;  three  nickel  plated  binding  posts  are  also  mounted 
on  the  base  and  so  connected  that  the  set  may  be  used  for 
individual  code  practice  or  for  operation  of  a  two  party  line, 
an  excellent  method  of  quickly  learning  the  code.  After  the 
beginner  has  mastered  the  code,  the  set  may  be  used  in  his 
wireless  outfit  for  setting  the  detector  in  adjustment,  and  also  the  key  may  be  used  to  control  the  spark  coil. 

Recommended  for  schools,  as  it  gives  excellent  service   for  class  instruction   in   code   work.      Full   direc- 
tions with  each  set. 
List  No.  Pnce 

342       Wireless  Practice  Set,  with  Red  Seal  Dry  Battery  and  Cord $2.70 

344      Wireless  Practice  Set  only,  no  battery  or  Cord $2.55 


STUDENT" 


This  set  is  similar  to  our  No.  342  except  that  it  has  an  80 
ohm  telephone  induction  coil  mounted  on  its  base. 

The  induction  coil  allows  the  operator  to  use  his  stand- 
ard radio  head  set,  any  number  in  parallel,  which  is  generally 
of  high  resistance  with  maximum  efficiency.  With  this  coil 
the  note  is  clear  without  discordance. 

This  set  is  particularly  adapted  for  instruction  purposes 
to  classes  of  wireless  students. 

Diagram   of  connections  with   each  instrument. 
List   No.  Price 

53       Student    Wireless    Practice    set $4.05 


This    outfit    consists    of   a    regular   telegraph   key   without  "UNIVERSITY 

circuit  breaker,  a  special   high   pitch   buzzer,   miniature  incan- 
descent lamp   with   socket,   switch,   five  binding  posts  and   c 
iso  ohm  induction  coil  mounted  on  a  polished  wood  base;  one 
RED   SEAL   Dry   Battery  and   four   feet   of  green   silk  double 
conducting  cord.  ,      , 

The  induction  coil  permits  the  operator  to  use  standard 
radio  head  srts  (any  number  in  parallel),  which  are  generally 
of  high  resisance  with  maximum  efficiency.  With  the  coil 
in  circuit  the  note  emitted  is  clear  and  distinct  without  dis- 
cordant tones.  , 

This   set    enables   the   student   to   acquire   both   sound  and 

List  No.  $4.50 

54       University    Practice    Set....  . 

Send  for  our  248  Page   Catalog  €28. 

Manhattan.  Electrical  Supply  Co.  Jnc. 


17   Park   Place, 
New    York 


114    S.   Wells    St., 
Chicago,    111 


1106    Pine    St., 
St.    Louis,    Mo. 


604   Mlssoii    St., 
San   Francisco,  Cal. 


88 


MARCONI    INSTITUTE 


7490-A 


P.EG.U.S.PAT.OFF.  &  FOREIGN  COUNTRIES, 


INSULATION 
"MADE  IN  AMERICA" 

LOUIS    STEINBERGER'S    PATENTS 


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SOLE  MANUFACTURERS 


66-82  Washington  St.     2  7-3  7  York  St. 
~      66-76  Front  St.  1-23  Flint  St. 

Brooklyn,  N.  Y.,  America 


MARCONI    INSTITUTE 


89 


tricity 

at  your  fingers  ends 

Know  the  facts  in  Electricity. 
They  count — and  mean  more 
money  and  better  position  for  you. 
You  need  the  exact  information, 
—  in  a  practical  form  so  that  you 
can  use  it  every  day,  to  help  you 
install  electrical  equipment,  or 
make  repairs,  or  operate  machines, 
of  do  whatever  else  your  present  job 
— or  the  job  ahead  of  you— calls  for. 

HAWKINS  ELECTRICAL  GUIDES 

help  you  succeed  through  electricity 

These  books  will  answer  every  one  of  your  electrical  problems.    They  are 
•ritten  so  that  you  can  understand  them.    Arranged  in  the  form  of  questions  you 
uld  ask — and  the  answers  to  them — in  plain,  practical,  everyday  language,  clear, 
ncise  and  to  the  point.    Thousands  of  men  are  using  Hawkins  Electrical  Guides 
a  practical  aid  to  greater  success  in  the  electrical  field. 


lead  what  users  say: 

very  Electrician,  Operating  Engineer  or  Student  who  wants  to 
vance  himself  in  the  Electrical  field  should  have  a  set  of  these 
oks."  JOHN  KELLEY,  116  Union  St.,  Newark,  Ohio. 

*'  For  the  man  not  getting  a  college  training,  and  even  in  that  case, 
,  I  can  sincerely  say  I  do  not  believe  there  is  a  better  set  of  books  on 
the  market  today."  LLOYD  D.  HUFFMAN,  Dayton,  Ohio. 

"  We  consider  Hawkins  Electrical  Guides  the  most  compact  and 
complete  set  of  electrical  references  in  the  market." 

NOGGLE  ELECTRIC  WOKKS,  Monterey,  Cal. 


44 1  think  they  should  be  in  the  hands  of  everyone  who  has  anything 
to  do  with  Electricity."  T.  E.  MURPHY,  Orange,  VaT 

"  For  the  practical  electrician,  they  are  the  best  books  published 
— worth  many  times  their  price."  1*,  C.  WAGNER,  Wyoming,  111. 
"  I  have  gained  valuable  information  from  them  which  has  helped 
me  directly  in  my  line  of  work." 

HERMAN  NODENBERG,  Hoboken,  N.  J. 

"They  are  wonderful  value.  Everything  is  so  clear  and  concise. 
Even  one  who  had  no  knowledge  of  Electricity  would  have  no  diffi- 
culty in  grasping  the  facts."  F.  L.  TAYLOR,  Amesbury,  Mass. 


*4  It  is  the  best  work  an  apprentice  can  study  if  he  wants  to  get  ahead 
de.  As  a  reference  for  the  experienced  worker  Hawkins 
l  Guides  are  unexcelled."  I.  MCCLELLAN,  Chillicothe,  Mo. 


in  his  trad 
Electri 


Specially  Arranged  for 
Home  Study  and  Reference 

They  are  bound  in  flexible 

covers  that  make  them  a  pleasure  to 
handle  or  have  in  your  library.  Size 
5x6%  inches  and  H  to  K  inches  thick. 
You  can  carry  each  separate 
volume  about  with  you  until  you  have 
mastered  its  contents.  Hawkins  Electri- 
cal Guides  fit  your  pocket  and  your 
pocket  book  as  well.  Only  $1  per  volume 
and  owners  of  the  set  say  there  are  no 
better  electrical  books  at  any  price. 

PARTIAL  CONTENTS 

Magnetism— Induction— Experiments  —  Dynamos 


Magnetism—  Induction—  Experiments  —  Dynamos 
—  Elec  trie  Machinery—  Motors—  Armatures—  Arm- 
ature Windings-  Installing  of  Dynamps—  Electri- 
cal Instrument  Testing:  — 

Wiring^wTrinsr  Diagrams—  Sign  Flashers-Stor- 


ng urrent  ysems  —  ircui  reaers  —  easur- 
ing Instruments—  Switch  Boards—  Wiring:—  Power 
Stations  —  Installing  —  Telephone  —  Telegraph  — 
Wireless—  Bells—  Lighting—  Railways.  Also  many 
Modern  Practical  Applications  of  Electricity 
and  Ready  Reference  Index  of  the  10  numbers. 


1O  Practical  Volumes  —  SSOO  Pages  —  47OO  Illustrations 

$1  A  Volume—  $1  A  Month 

These  books  are  a  complete  and  up-to-date  course  in  Electrical 

Engineering—  the  standard  works  on  Electrical  Science.    Contain  no     ^ 
useless  matter—  only  such  information  as  is  needed. 

Shipped  to  You  FREE 


Bend  no  money.    Examine  the  books  first.    Decide 

for  yourself  that  they  are  the  most  complete  and  clearest 

written  electrical  books  ever  published.  Every  book 

is  complete  in  itself  but  the  entire  set  is  the  best 

bargain.     Accept  this  unusual  offer  no 

mail  the  coupon  today.    If  you  decide 

to  keep  the  books  you  can  make 

settlement    at    only    $1    per 

month,  until  paid  for. 


&Co. 
SthAve.,N.Y. 

Please  submit  me  for  ex- 
amination Hawkins  Electrical 
(Price  $1  each).    Ship  at 
once,  prepaid,   the   10   numbers.     If 
satisfactory  I  agree  to  send  you  $1  within 
fcys  and  to  further  mail  you  $1  each 


Signature. 


Occupation. 

Business  Address 

Residence.... 


90  MARCONI    INSTITUTE 

missssssssssss^^ 

Thermo  -  Galvanometer 

Type  115 


For    High    Frequency   Measurements 
PRICE   $28.00 

General  Radio  Co.,  Cambridge,  Mass. 


Teach  the  Code  With  the  OMNIGRAPH 

The  Omnigraph  Automatic  Transmitter  will  teach  your  students  the  Continental  and  the 
Morse  Codes  in  half  the  usual  time  and  at  the  least  possible  expense. 

The  Omnigraph,  connected  with  Buzzer  or  Sounder,  will  send  unlimited  Wireless  or  Morse 
Code  messages,  £3;  the  hour  and  at  any  speed  you  desire.  Invaluable  also  for  practice  with 
the  Morse  Light,  allowing  students  to  quickly  master  the  Blinker  system. 

We  offer  the  Omnigraph  as  a  positive  success  and  with  the  strongest  of  endorsements.  It  has 
been  adopted  by  the  U.  S.  Government,  Dept.  of  Commerce,  and  is  used  to  test  all  operators 
applying  for  Radio  licenses.  Other  Departments  of  the  Government  use  it  for  instruction 
purposes  and  a  large  number  of  the  leading  Universities,  Colleges,  Technical  and  Telegraph 
Schools  throughout  the  U.  S.  are  satisfied  purchasers  of  the  Omnigraph.  Thousands  of  in- 
dividuals have  quickly  learned  with  it. 

It  will  make  your  students  operators  in  the  shortest  possible  time.  For  the  student  who  is 
an  operator,  it  will  make  him  a  better  one.  Especially  at  this  time,  there  is  nothing  to 

compare  with  the   Omnigraph   for  keeping 

up  Code  practice. 

Send  for  free  catalog  describing  3  different 
models — $8.00  to  $20.00 — or  order  direct 
through  your  Electrical  Dealer.  We  sell  the 
Omnigraph  under  the  strongest  of  guaran- 
tees— you  must  be  satisfied  or  your  money 
back. 

The  Omnigraph  Mfg.  Co. 

35-39  CORTLANDT  ST.         NEW  YORK 
How  did  you  learn  to  talk?  By  listening.       JUST  LISTEN— THE  OMNIGRAPH  WILL  DO  THE  TEACHING 


MARCONI    INSTITUTE 


91 


Use  the  Bronx  Buzzer 
in  Your  Radio  Class 


T 


Bronx  Buzzer 
for  Wireless 
Practice  Use. 


HIS  Buzzer  is  the  one  that  is  used  by  the  most  progressive  in- 
structors in  wireless. 

Its  quick  response  to  the  key  and  its  clear,  easily  heard  tone 
makes  it  a  general  favorite  in  class  and  private  use. 

Marconi  Instructors  recommend  the  use  of  the  Bronx  in  private 
class  work  in  preference  to  any  other  buzzer. 

You  will  find  students  learn  the  code  very  quickly  when  it  is 
taught  with  the  Bronx  and  they  gain  speed  rapidly  on  account  of  the 
close  resemblance  of  the  tone  of  this  buzzer  to  the  sound  of  the  reg- 
ular wireless  spark. 


Our  practice  set  consisting  of  key,   buzzer  and  binding  posts  mounted  on 
hard  wood  panel   is  particularly  adapted  for  school  use. 

Write  for  full  particulars. 

EDWARD^COAPA/tY 

Factory:    140th  and  Exterior  Streets,  New  York 


BELDEN 

STANDARD   PRODUCTS 


Coil  Windings 

Magnet  Wire 

Cords  and  Cordage 

Rubber  Covered  Wire 

Litzendraht  Wire 

Antenna  Wire 

Copper  Connectors  and  Pigtails 

Molded  Parts 

Bakelite  Dilecto  Fibre 


BELDEN    MFG.   CO. 


2311    S.   WESTERN    AVENUE 
CHICAGO,   ILL. 


92 


MARCONI    INSTITUTE 


Longmans'  Books  on  Wireless  Telegraphy 

TEXT-BOOK  ON  WIRELESS  TELEGRAPHY 

By  RUPERT  STANLEY,  B.A.,  M.I.E.E.,  Professor  of  Physics  and  Electrical  Engineer- 
ing, Municipal  Technical  Institute,  Belfast;  Extra  Mural  Professor  of  Electrical  Engi- 
neering, Queen's  University,  Belfast.  With  202  Illustrations  and  Plates.  8vo.  Fourth 
impression.  $2.50  net. 

"Professor  Stanley  has  given  us  a  very  useful  book  indeed  ...  in  this  well  illustrated  and  complete 
work.  The  formulas  necessary  are  cited  and  explained  in  a  clear  and  up-to-date  manner.  The  style  of  the 
book  is  such  that  the  beginner  in  the  art  can  learn  from  it  as  well  as  the  expert.  Many  new  subjects  are 
covered  in  the  various  chapters  and  it  will  pay  everyone  interested  to  read  it  thru." — Electrical  Experi- 
menter. 

PRINCIPLES  OF  ELECTRIC  WAVE  TELEGRAPHY  AND  TELEPHONY 
By  J.  A.  FLEMING,  M.A.,  D.Sc.,  F.R.S.,  Fender  Professor  of  Electrical  Engineering 

in  the  University  of  London,  etc.     Third  edition.    Fully  Revised  and  Extended.     With 

Plates  and  numerous  other  illustrations.    8vo.    $10.00  net. 
"This   excellent   treatise   on   the   principles   and    apparatus    employed   in    radio-telegraphy   and    telephony 

here  appears  in  its  third  edition The  book  has  been  carefully  revised  and  brought  up-to-date.    It 

offers  to  the  student  of  the  radio-communication  principles  what  is   probably   the  most  complete   and   com- 
prehensive treatise  in  the  English  language." — Electrical  World. 

AN  ELEMENTARY  MANUAL  OF  RADIO-TELEGRAPHY  AND  RADIO- 
TELEPHONY  FOR  STUDENTS  AND  OPERATORS 

By  the  Same  Author.     Third  Edition,  Revised.     With  194  Illustrations.     8vo.     $2.50  net. 

"It  remains  the  best  introduction  to  the  subject  for  all  students,  and  a  sufficient  manual  for  those 
who  intend  to  take  up  the  practical  application,  but  who  do  not  wish  to  go  too  deeply  into  the  theoretical 
and  mathematical  side." — Nature. 

LONGMANS,  GREEN  &  CO.,  Publishers 

Fourth  Avenue  and  30th  Street,  New  York 


Not  only 

WIRELESS  BOOKS 

but  books  of  all  kinds  are  included 
in  our  unusually  large  stock  of  the 
books  of  all  publishers. 

Our  location  in  the  publishing  cen- 
ter of  the  country  enables  us  to 
secure  quickly  any  title  that  we 
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A  MARCONI  CONTRACT 

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MEANS 


Elimination  of  the  ship-owners'  responsibility 
concerning  maintenance  of  the  apparatus. 

Compliance  with  Government  Regulations, 
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Modern  Apparatus 

The  result  of  years  of  research  and  develop- 
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Efficient  Operation 

By  trained  men  developed  in  our  organization 
who  have  made  reliable  communication  by 
wireless  practicable. 

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At  Honolulu,  the  Crossroads  of  the  Pacific,  the  largest  wireless  sta- 
tion in  the  world  relays  these  trans-oceanic  messages.  At  both  Honolulu 
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MARCONI 


95 


How  to  Conduct  a 
Radio  Club 

New  Edition— Revised  and  Enlarged 

Elmer  E.  Bucher 

Completely  revised  and  enlarged,  this 
useful  volume  is  once  more  presented  to 
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telegraphic  equipment. 

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8vo.      61/3x91/2.       134    Illustrations. 

Price  50c   net. 

With  One  Year's  Subscription  to  the  Wire- 
less Age  $2.00 

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In  this  illustrated  monthly  magazine  of  radio  com- 
munication every  new  achievement  is  reported,  and  all 
the  latest  improvements  and  developments  in  the  prog- 
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You  need  this  information.  No  radio  engineer  or 
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Instructive  articles  by  experts  appear  each  month. 
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PRACTICAL  TRAINING  COURSES  in  the  following  branches,  of  which  there  i*  urgent  need: 

AVIATION  NAVIGATION 


Conducted    by    HENRY    WOODHOUSE 
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Conducted    by    CAPT.    F.    E.    UTTMARK 
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WIRELESS  TELEGRAPHY     SIGNAL  CORPS  WORK 


Conducted  by  ELMER  E.  BUCHER, 
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Conducted    by    Major    J.    ANDREW    WHITE, 
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96 


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QUALITY-and 

someihina  more 


THE  superiority  of  our  wireless 
apparatus  has  brought  us  many 
orders  from  schools  and   col- 
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customers    some    of    the    leading 
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They  have  learned  that  the  apparatus 
sold  by  Sears,  Roebuck  and  Co.  can  be 
judged  by  every  test  of  quality  and  value 
and  that  it  will  not  be  found  wanting. 

But  there  is  something  more  to  our 
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For  those  who  are  interested  in  wire- 
less apparatus  we  publish  a  very  complete 
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We  also  sell  telegraph  instruments 
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us  to  send  our  Catalog  of  Electrical  Mer- 
chandise No.  71W29B. 


Sears,  Roebuck  and  Co. 
Chicago 


of 


1917-18   Edition 


The  Year  Book  of 
ireless  Telegraphy  and 
Telephony 

nly  C°mprelieilsive  Reference  Work  on  Wireless 


telegraphy;  ^  regulations 
stations  throughout  the  world  call  lerteT         '  ,comPlete  lis*>  of  ship  an* 

>*^^ 

.    Also  a  full  «  "** 


Furnishes  Latest  and  Most  Valuable  Data,  including 

3 


?he 

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Persistent 


c  Oscillations. 


of  Wireless   Telegraphy 


in  five 
International  Units  and  Symbols 

Biographical  Notices. 

Literature  of  Wireless  Telegraphy 

Directory  of  Wireless  Societies 

Code  Signals. 

International  Time  and  Weather  Signals. 

Wireless  Map  of  the  World. 

Octavo.    Cloth.    Fully  Illustrated.     Over  1,000  Pages 
PRICE,  $2.00  net.    Postage  20e  extra 


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